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| <section id="row-to-columnar-conversion"> |
| <h1>Row to columnar conversion<a class="headerlink" href="#row-to-columnar-conversion" title="Permalink to this heading">#</a></h1> |
| <section id="fixed-schemas"> |
| <h2>Fixed Schemas<a class="headerlink" href="#fixed-schemas" title="Permalink to this heading">#</a></h2> |
| <p>The following example converts an array of structs to a <a class="reference internal" href="../api/table.html#_CPPv4N5arrow5TableE" title="arrow::Table"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">arrow::Table</span></code></a> |
| instance, and then converts it back to the original array of structs.</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="c1">// Licensed to the Apache Software Foundation (ASF) under one</span> |
| <span class="c1">// or more contributor license agreements. See the NOTICE file</span> |
| <span class="c1">// distributed with this work for additional information</span> |
| <span class="c1">// regarding copyright ownership. The ASF licenses this file</span> |
| <span class="c1">// to you under the Apache License, Version 2.0 (the</span> |
| <span class="c1">// "License"); you may not use this file except in compliance</span> |
| <span class="c1">// with the License. You may obtain a copy of the License at</span> |
| <span class="c1">//</span> |
| <span class="c1">// http://www.apache.org/licenses/LICENSE-2.0</span> |
| <span class="c1">//</span> |
| <span class="c1">// Unless required by applicable law or agreed to in writing,</span> |
| <span class="c1">// software distributed under the License is distributed on an</span> |
| <span class="c1">// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY</span> |
| <span class="c1">// KIND, either express or implied. See the License for the</span> |
| <span class="c1">// specific language governing permissions and limitations</span> |
| <span class="c1">// under the License.</span> |
| |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><arrow/api.h></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><arrow/result.h></span> |
| |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><cstdint></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><iomanip></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><iostream></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><vector></span> |
| |
| <span class="k">using</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">DoubleBuilder</span><span class="p">;</span> |
| <span class="k">using</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Builder</span><span class="p">;</span> |
| <span class="k">using</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ListBuilder</span><span class="p">;</span> |
| |
| <span class="c1">// While we want to use columnar data structures to build efficient operations, we</span> |
| <span class="c1">// often receive data in a row-wise fashion from other systems. In the following,</span> |
| <span class="c1">// we want give a brief introduction into the classes provided by Apache Arrow by</span> |
| <span class="c1">// showing how to transform row-wise data into a columnar table.</span> |
| <span class="c1">//</span> |
| <span class="c1">// The table contains an id for a product, the number of components in the product</span> |
| <span class="c1">// and the cost of each component.</span> |
| <span class="c1">//</span> |
| <span class="c1">// The data in this example is stored in the following struct:</span> |
| <span class="k">struct</span><span class="w"> </span><span class="nc">data_row</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">id</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">components</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="kt">double</span><span class="o">></span><span class="w"> </span><span class="n">component_cost</span><span class="p">;</span> |
| <span class="p">};</span> |
| |
| <span class="c1">// Transforming a vector of structs into a columnar Table.</span> |
| <span class="c1">//</span> |
| <span class="c1">// The final representation should be an `arrow::Table` which in turn</span> |
| <span class="c1">// is made up of an `arrow::Schema` and a list of</span> |
| <span class="c1">// `arrow::ChunkedArray` instances. As the first step, we will iterate</span> |
| <span class="c1">// over the data and build up the arrays incrementally. For this</span> |
| <span class="c1">// task, we provide `arrow::ArrayBuilder` classes that help in the</span> |
| <span class="c1">// construction of the final `arrow::Array` instances.</span> |
| <span class="c1">//</span> |
| <span class="c1">// For each type, Arrow has a specially typed builder class. For the primitive</span> |
| <span class="c1">// values `id` and `components` we can use the `arrow::Int64Builder`. For the</span> |
| <span class="c1">// `component_cost` vector, we need to have two builders, a top-level</span> |
| <span class="c1">// `arrow::ListBuilder` that builds the array of offsets and a nested</span> |
| <span class="c1">// `arrow::DoubleBuilder` that constructs the underlying values array that</span> |
| <span class="c1">// is referenced by the offsets in the former array.</span> |
| <span class="n">arrow</span><span class="o">::</span><span class="n">Result</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Table</span><span class="o">>></span><span class="w"> </span><span class="n">VectorToColumnarTable</span><span class="p">(</span> |
| <span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="k">struct</span><span class="w"> </span><span class="nc">data_row</span><span class="o">>&</span><span class="w"> </span><span class="n">rows</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="c1">// The builders are more efficient using</span> |
| <span class="w"> </span><span class="c1">// arrow::jemalloc::MemoryPool::default_pool() as this can increase the size of</span> |
| <span class="w"> </span><span class="c1">// the underlying memory regions in-place. At the moment, arrow::jemalloc is only</span> |
| <span class="w"> </span><span class="c1">// supported on Unix systems, not Windows.</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MemoryPool</span><span class="o">*</span><span class="w"> </span><span class="n">pool</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">default_memory_pool</span><span class="p">();</span> |
| |
| <span class="w"> </span><span class="n">Int64Builder</span><span class="w"> </span><span class="nf">id_builder</span><span class="p">(</span><span class="n">pool</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">Int64Builder</span><span class="w"> </span><span class="nf">components_builder</span><span class="p">(</span><span class="n">pool</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">ListBuilder</span><span class="w"> </span><span class="nf">component_cost_builder</span><span class="p">(</span><span class="n">pool</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">make_shared</span><span class="o"><</span><span class="n">DoubleBuilder</span><span class="o">></span><span class="p">(</span><span class="n">pool</span><span class="p">));</span> |
| <span class="w"> </span><span class="c1">// The following builder is owned by component_cost_builder.</span> |
| <span class="w"> </span><span class="n">DoubleBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">component_item_cost_builder</span><span class="w"> </span><span class="o">=</span> |
| <span class="w"> </span><span class="p">(</span><span class="k">static_cast</span><span class="o"><</span><span class="n">DoubleBuilder</span><span class="o">*></span><span class="p">(</span><span class="n">component_cost_builder</span><span class="p">.</span><span class="n">value_builder</span><span class="p">()));</span> |
| |
| <span class="w"> </span><span class="c1">// Now we can loop over our existing data and insert it into the builders. The</span> |
| <span class="w"> </span><span class="c1">// `Append` calls here may fail (e.g. we cannot allocate enough additional memory).</span> |
| <span class="w"> </span><span class="c1">// Thus we need to check their return values. For more information on these values,</span> |
| <span class="w"> </span><span class="c1">// check the documentation about `arrow::Status`.</span> |
| <span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">data_row</span><span class="o">&</span><span class="w"> </span><span class="n">row</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">rows</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">id_builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="n">row</span><span class="p">.</span><span class="n">id</span><span class="p">));</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">components_builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="n">row</span><span class="p">.</span><span class="n">components</span><span class="p">));</span> |
| |
| <span class="w"> </span><span class="c1">// Indicate the start of a new list row. This will memorise the current</span> |
| <span class="w"> </span><span class="c1">// offset in the values builder.</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">component_cost_builder</span><span class="p">.</span><span class="n">Append</span><span class="p">());</span> |
| <span class="w"> </span><span class="c1">// Store the actual values. The same memory layout is</span> |
| <span class="w"> </span><span class="c1">// used for the component cost data, in this case a vector of</span> |
| <span class="w"> </span><span class="c1">// type double, as for the memory that Arrow uses to hold this</span> |
| <span class="w"> </span><span class="c1">// data and will be created.</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">component_item_cost_builder</span><span class="o">-></span><span class="n">AppendValues</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">row</span><span class="p">.</span><span class="n">component_cost</span><span class="p">.</span><span class="n">data</span><span class="p">(),</span><span class="w"> </span><span class="n">row</span><span class="p">.</span><span class="n">component_cost</span><span class="p">.</span><span class="n">size</span><span class="p">()));</span> |
| <span class="w"> </span><span class="p">}</span> |
| |
| <span class="w"> </span><span class="c1">// At the end, we finalise the arrays, declare the (type) schema and combine them</span> |
| <span class="w"> </span><span class="c1">// into a single `arrow::Table`:</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">id_array</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">id_builder</span><span class="p">.</span><span class="n">Finish</span><span class="p">(</span><span class="o">&</span><span class="n">id_array</span><span class="p">));</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">components_array</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">components_builder</span><span class="p">.</span><span class="n">Finish</span><span class="p">(</span><span class="o">&</span><span class="n">components_array</span><span class="p">));</span> |
| <span class="w"> </span><span class="c1">// No need to invoke component_item_cost_builder.Finish because it is implied by</span> |
| <span class="w"> </span><span class="c1">// the parent builder's Finish invocation.</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">component_cost_array</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">component_cost_builder</span><span class="p">.</span><span class="n">Finish</span><span class="p">(</span><span class="o">&</span><span class="n">component_cost_array</span><span class="p">));</span> |
| |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">>></span><span class="w"> </span><span class="n">schema_vector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">field</span><span class="p">(</span><span class="s">"id"</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">int64</span><span class="p">()),</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">field</span><span class="p">(</span><span class="s">"components"</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">int64</span><span class="p">()),</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">field</span><span class="p">(</span><span class="s">"component_cost"</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">list</span><span class="p">(</span><span class="n">arrow</span><span class="o">::</span><span class="n">float64</span><span class="p">()))};</span> |
| |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">schema</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">make_shared</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Schema</span><span class="o">></span><span class="p">(</span><span class="n">schema_vector</span><span class="p">);</span> |
| |
| <span class="w"> </span><span class="c1">// The final `table` variable is the one we can then pass on to other functions</span> |
| <span class="w"> </span><span class="c1">// that can consume Apache Arrow memory structures. This object has ownership of</span> |
| <span class="w"> </span><span class="c1">// all referenced data, thus we don't have to care about undefined references once</span> |
| <span class="w"> </span><span class="c1">// we leave the scope of the function building the table and its underlying arrays.</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Table</span><span class="o">></span><span class="w"> </span><span class="n">table</span><span class="w"> </span><span class="o">=</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Table</span><span class="o">::</span><span class="n">Make</span><span class="p">(</span><span class="n">schema</span><span class="p">,</span><span class="w"> </span><span class="p">{</span><span class="n">id_array</span><span class="p">,</span><span class="w"> </span><span class="n">components_array</span><span class="p">,</span><span class="w"> </span><span class="n">component_cost_array</span><span class="p">});</span> |
| |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">table</span><span class="p">;</span> |
| <span class="p">}</span> |
| |
| <span class="n">arrow</span><span class="o">::</span><span class="n">Result</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">data_row</span><span class="o">>></span><span class="w"> </span><span class="n">ColumnarTableToVector</span><span class="p">(</span> |
| <span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Table</span><span class="o">>&</span><span class="w"> </span><span class="n">table</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="c1">// To convert an Arrow table back into the same row-wise representation as in the</span> |
| <span class="w"> </span><span class="c1">// above section, we first will check that the table conforms to our expected</span> |
| <span class="w"> </span><span class="c1">// schema and then will build up the vector of rows incrementally.</span> |
| <span class="w"> </span><span class="c1">//</span> |
| <span class="w"> </span><span class="c1">// For the check if the table is as expected, we can utilise solely its schema.</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">>></span><span class="w"> </span><span class="n">schema_vector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">field</span><span class="p">(</span><span class="s">"id"</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">int64</span><span class="p">()),</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">field</span><span class="p">(</span><span class="s">"components"</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">int64</span><span class="p">()),</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">field</span><span class="p">(</span><span class="s">"component_cost"</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">list</span><span class="p">(</span><span class="n">arrow</span><span class="o">::</span><span class="n">float64</span><span class="p">()))};</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">expected_schema</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">make_shared</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Schema</span><span class="o">></span><span class="p">(</span><span class="n">schema_vector</span><span class="p">);</span> |
| |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">expected_schema</span><span class="o">-></span><span class="n">Equals</span><span class="p">(</span><span class="o">*</span><span class="n">table</span><span class="o">-></span><span class="n">schema</span><span class="p">()))</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="c1">// The table doesn't have the expected schema thus we cannot directly</span> |
| <span class="w"> </span><span class="c1">// convert it to our target representation.</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">Invalid</span><span class="p">(</span><span class="s">"Schemas are not matching!"</span><span class="p">);</span> |
| <span class="w"> </span><span class="p">}</span> |
| |
| <span class="w"> </span><span class="c1">// As we have ensured that the table has the expected structure, we can unpack the</span> |
| <span class="w"> </span><span class="c1">// underlying arrays. For the primitive columns `id` and `components` we can use the</span> |
| <span class="w"> </span><span class="c1">// high level functions to get the values whereas for the nested column</span> |
| <span class="w"> </span><span class="c1">// `component_costs` we need to access the C-pointer to the data to copy its</span> |
| <span class="w"> </span><span class="c1">// contents into the resulting `std::vector<double>`. Here we need to be careful to</span> |
| <span class="w"> </span><span class="c1">// also add the offset to the pointer. This offset is needed to enable zero-copy</span> |
| <span class="w"> </span><span class="c1">// slicing operations. While this could be adjusted automatically for double</span> |
| <span class="w"> </span><span class="c1">// arrays, this cannot be done for the accompanying bitmap as often the slicing</span> |
| <span class="w"> </span><span class="c1">// border would be inside a byte.</span> |
| |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">ids</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">static_pointer_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Array</span><span class="o">></span><span class="p">(</span><span class="n">table</span><span class="o">-></span><span class="n">column</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span><span class="o">-></span><span class="n">chunk</span><span class="p">(</span><span class="mi">0</span><span class="p">));</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">components</span><span class="w"> </span><span class="o">=</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">static_pointer_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Array</span><span class="o">></span><span class="p">(</span><span class="n">table</span><span class="o">-></span><span class="n">column</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span><span class="o">-></span><span class="n">chunk</span><span class="p">(</span><span class="mi">0</span><span class="p">));</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">component_cost</span><span class="w"> </span><span class="o">=</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">static_pointer_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">ListArray</span><span class="o">></span><span class="p">(</span><span class="n">table</span><span class="o">-></span><span class="n">column</span><span class="p">(</span><span class="mi">2</span><span class="p">)</span><span class="o">-></span><span class="n">chunk</span><span class="p">(</span><span class="mi">0</span><span class="p">));</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">component_cost_values</span><span class="w"> </span><span class="o">=</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">static_pointer_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">DoubleArray</span><span class="o">></span><span class="p">(</span><span class="n">component_cost</span><span class="o">-></span><span class="n">values</span><span class="p">());</span> |
| <span class="w"> </span><span class="c1">// To enable zero-copy slices, the native values pointer might need to account</span> |
| <span class="w"> </span><span class="c1">// for this slicing offset. This is not needed for the higher level functions</span> |
| <span class="w"> </span><span class="c1">// like Value(…) that already account for this offset internally.</span> |
| <span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">double</span><span class="o">*</span><span class="w"> </span><span class="n">ccv_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">component_cost_values</span><span class="o">-></span><span class="n">raw_values</span><span class="p">();</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">data_row</span><span class="o">></span><span class="w"> </span><span class="n">rows</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">table</span><span class="o">-></span><span class="n">num_rows</span><span class="p">();</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="c1">// Another simplification in this example is that we assume that there are</span> |
| <span class="w"> </span><span class="c1">// no null entries, e.g. each row is fill with valid values.</span> |
| <span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">id</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ids</span><span class="o">-></span><span class="n">Value</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">component</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">components</span><span class="o">-></span><span class="n">Value</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">double</span><span class="o">*</span><span class="w"> </span><span class="n">first</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ccv_ptr</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">component_cost</span><span class="o">-></span><span class="n">value_offset</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">double</span><span class="o">*</span><span class="w"> </span><span class="n">last</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ccv_ptr</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">component_cost</span><span class="o">-></span><span class="n">value_offset</span><span class="p">(</span><span class="n">i</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="kt">double</span><span class="o">></span><span class="w"> </span><span class="n">components_vec</span><span class="p">(</span><span class="n">first</span><span class="p">,</span><span class="w"> </span><span class="n">last</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">rows</span><span class="p">.</span><span class="n">push_back</span><span class="p">({</span><span class="n">id</span><span class="p">,</span><span class="w"> </span><span class="n">component</span><span class="p">,</span><span class="w"> </span><span class="n">components_vec</span><span class="p">});</span> |
| <span class="w"> </span><span class="p">}</span> |
| |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">rows</span><span class="p">;</span> |
| <span class="p">}</span> |
| |
| <span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">RunRowConversion</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">data_row</span><span class="o">></span><span class="w"> </span><span class="n">original_rows</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="p">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p">{</span><span class="mf">10.0</span><span class="p">}},</span><span class="w"> </span><span class="p">{</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="p">{</span><span class="mf">11.0</span><span class="p">,</span><span class="w"> </span><span class="mf">12.0</span><span class="p">,</span><span class="w"> </span><span class="mf">13.0</span><span class="p">}},</span><span class="w"> </span><span class="p">{</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p">{</span><span class="mf">15.0</span><span class="p">,</span><span class="w"> </span><span class="mf">25.0</span><span class="p">}}};</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Table</span><span class="o">></span><span class="w"> </span><span class="n">table</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">data_row</span><span class="o">></span><span class="w"> </span><span class="n">converted_rows</span><span class="p">;</span> |
| |
| <span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="n">table</span><span class="p">,</span><span class="w"> </span><span class="n">VectorToColumnarTable</span><span class="p">(</span><span class="n">original_rows</span><span class="p">));</span> |
| |
| <span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="n">converted_rows</span><span class="p">,</span><span class="w"> </span><span class="n">ColumnarTableToVector</span><span class="p">(</span><span class="n">table</span><span class="p">));</span> |
| |
| <span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="n">original_rows</span><span class="p">.</span><span class="n">size</span><span class="p">()</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">converted_rows</span><span class="p">.</span><span class="n">size</span><span class="p">());</span> |
| |
| <span class="w"> </span><span class="c1">// Print out contents of table, should get</span> |
| <span class="w"> </span><span class="c1">// ID Components Component prices</span> |
| <span class="w"> </span><span class="c1">// 1 1 10</span> |
| <span class="w"> </span><span class="c1">// 2 3 11 12 13</span> |
| <span class="w"> </span><span class="c1">// 3 2 15 25</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">left</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">setw</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"ID "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">left</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">setw</span><span class="p">(</span><span class="mi">11</span><span class="p">)</span> |
| <span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Components "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">left</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">setw</span><span class="p">(</span><span class="mi">15</span><span class="p">)</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Component prices "</span> |
| <span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">row</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">converted_rows</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">left</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">setw</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">row</span><span class="p">.</span><span class="n">id</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">left</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">setw</span><span class="p">(</span><span class="mi">11</span><span class="p">)</span> |
| <span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">row</span><span class="p">.</span><span class="n">components</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">cost</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">row</span><span class="p">.</span><span class="n">component_cost</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">left</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">setw</span><span class="p">(</span><span class="mi">4</span><span class="p">)</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">cost</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="p">}</span> |
| |
| <span class="kt">int</span><span class="w"> </span><span class="n">main</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">argc</span><span class="p">,</span><span class="w"> </span><span class="kt">char</span><span class="o">**</span><span class="w"> </span><span class="n">argv</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">status</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RunRowConversion</span><span class="p">();</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">status</span><span class="p">.</span><span class="n">ok</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cerr</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">status</span><span class="p">.</span><span class="n">ToString</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_FAILURE</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_SUCCESS</span><span class="p">;</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| </section> |
| <section id="dynamic-schemas"> |
| <h2>Dynamic Schemas<a class="headerlink" href="#dynamic-schemas" title="Permalink to this heading">#</a></h2> |
| <p>In many cases, we need to convert to and from row data that does not have a |
| schema known at compile time. To help implement these conversions, this library |
| provides several utilities:</p> |
| <ul class="simple"> |
| <li><p><a class="reference internal" href="../api/builder.html#_CPPv4N5arrow18RecordBatchBuilderE" title="arrow::RecordBatchBuilder"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">arrow::RecordBatchBuilder</span></code></a>: creates and manages array builders for |
| a full record batch.</p></li> |
| <li><p><a class="reference internal" href="../api/utilities.html#_CPPv4I0DpEN5arrow15VisitTypeInlineE6StatusRK8DataTypeP7VISITORDpRR4ARGS" title="arrow::VisitTypeInline"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">arrow::VisitTypeInline()</span></code></a>: dispatch to functions specialized for the given |
| array type.</p></li> |
| <li><p><a class="reference internal" href="../api/utilities.html#type-traits"><span class="std std-ref">Type Traits</span></a> (such as <code class="docutils literal notranslate"><span class="pre">arrow::enable_if_primitive_ctype</span></code>): narrow template |
| functions to specific Arrow types, useful in conjunction with |
| the <a class="reference internal" href="../datatypes.html#cpp-visitor-pattern"><span class="std std-ref">Visitor Pattern</span></a>.</p></li> |
| <li><p><a class="reference internal" href="../api/table.html#_CPPv4N5arrow16TableBatchReaderE" title="arrow::TableBatchReader"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">arrow::TableBatchReader</span></code></a>: read a table in a batch at a time, with each |
| batch being a zero-copy slice.</p></li> |
| </ul> |
| <p>The following example shows how to implement conversion between <code class="docutils literal notranslate"><span class="pre">rapidjson::Document</span></code> |
| and Arrow objects. You can read the full code example at |
| <a class="github reference external" href="https://github.com/apache/arrow/blob/main/cpp/examples/arrow/rapidjson_row_converter.cc">apache/arrow</a></p> |
| <section id="writing-conversions-to-arrow"> |
| <h3>Writing conversions to Arrow<a class="headerlink" href="#writing-conversions-to-arrow" title="Permalink to this heading">#</a></h3> |
| <p>To convert rows to Arrow record batches, we’ll setup Array builders for all the columns |
| and then for each field iterate through row values and append to the builders. |
| We assume that we already know the target schema, which may have |
| been provided by another system or was inferred in another function. Inferring |
| the schema <em>during</em> conversion is a challenging proposition; many systems will |
| check the first N rows to infer a schema if there is none already available.</p> |
| <p>At the top level, we define a function <code class="docutils literal notranslate"><span class="pre">ConvertToRecordBatch</span></code>:</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="linenos">495</span><span class="n">arrow</span><span class="o">::</span><span class="n">Result</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatch</span><span class="o">>></span><span class="w"> </span><span class="n">ConvertToRecordBatch</span><span class="p">(</span> |
| <span class="linenos">496</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">>&</span><span class="w"> </span><span class="n">rows</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Schema</span><span class="o">></span><span class="w"> </span><span class="n">schema</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">497</span><span class="w"> </span><span class="c1">// RecordBatchBuilder will create array builders for us for each field in our</span> |
| <span class="linenos">498</span><span class="w"> </span><span class="c1">// schema. By passing the number of output rows (`rows.size()`) we can</span> |
| <span class="linenos">499</span><span class="w"> </span><span class="c1">// pre-allocate the correct size of arrays, except of course in the case of</span> |
| <span class="linenos">500</span><span class="w"> </span><span class="c1">// string, byte, and list arrays, which have dynamic lengths.</span> |
| <span class="linenos">501</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatchBuilder</span><span class="o">></span><span class="w"> </span><span class="n">batch_builder</span><span class="p">;</span> |
| <span class="linenos">502</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span> |
| <span class="linenos">503</span><span class="w"> </span><span class="n">batch_builder</span><span class="p">,</span> |
| <span class="linenos">504</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatchBuilder</span><span class="o">::</span><span class="n">Make</span><span class="p">(</span><span class="n">schema</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">default_memory_pool</span><span class="p">(),</span><span class="w"> </span><span class="n">rows</span><span class="p">.</span><span class="n">size</span><span class="p">()));</span> |
| <span class="linenos">505</span> |
| <span class="linenos">506</span><span class="w"> </span><span class="c1">// Inner converter will take rows and be responsible for appending values</span> |
| <span class="linenos">507</span><span class="w"> </span><span class="c1">// to provided array builders.</span> |
| <span class="linenos">508</span><span class="w"> </span><span class="n">JsonValueConverter</span><span class="w"> </span><span class="nf">converter</span><span class="p">(</span><span class="n">rows</span><span class="p">);</span> |
| <span class="linenos">509</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">batch_builder</span><span class="o">-></span><span class="n">num_fields</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">510</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">></span><span class="w"> </span><span class="n">field</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">schema</span><span class="o">-></span><span class="n">field</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="linenos">511</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">batch_builder</span><span class="o">-></span><span class="n">GetField</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="linenos">512</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">converter</span><span class="p">.</span><span class="n">Convert</span><span class="p">(</span><span class="o">*</span><span class="n">field</span><span class="p">.</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="n">builder</span><span class="p">));</span> |
| <span class="linenos">513</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">514</span> |
| <span class="linenos">515</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatch</span><span class="o">></span><span class="w"> </span><span class="n">batch</span><span class="p">;</span> |
| <span class="linenos">516</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="n">batch</span><span class="p">,</span><span class="w"> </span><span class="n">batch_builder</span><span class="o">-></span><span class="n">Flush</span><span class="p">());</span> |
| <span class="linenos">517</span> |
| <span class="linenos">518</span><span class="w"> </span><span class="c1">// Use RecordBatch::ValidateFull() to make sure arrays were correctly constructed.</span> |
| <span class="linenos">519</span><span class="w"> </span><span class="n">DCHECK_OK</span><span class="p">(</span><span class="n">batch</span><span class="o">-></span><span class="n">ValidateFull</span><span class="p">());</span> |
| <span class="linenos">520</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">batch</span><span class="p">;</span> |
| <span class="linenos">521</span><span class="p">}</span><span class="w"> </span><span class="c1">// ConvertToRecordBatch</span> |
| </pre></div> |
| </div> |
| <p>First we use <a class="reference internal" href="../api/builder.html#_CPPv4N5arrow18RecordBatchBuilderE" title="arrow::RecordBatchBuilder"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">arrow::RecordBatchBuilder</span></code></a>, which conveniently creates builders |
| for each field in the schema. Then we iterate over the fields of the schema, get |
| the builder, and call <code class="docutils literal notranslate"><span class="pre">Convert()</span></code> on our <code class="docutils literal notranslate"><span class="pre">JsonValueConverter</span></code> (to be discussed |
| next). At the end, we call <code class="docutils literal notranslate"><span class="pre">batch->ValidateFull()</span></code>, which checks the integrity |
| of our arrays to make sure the conversion was performed correctly, which is useful |
| for debugging new conversion implementations.</p> |
| <p>One level down, the <code class="docutils literal notranslate"><span class="pre">JsonValueConverter</span></code> is responsible for appending row values |
| for the provided field to a provided array builder. In order to specialize logic |
| for each data type, it implements <code class="docutils literal notranslate"><span class="pre">Visit</span></code> methods and calls <a class="reference internal" href="../api/utilities.html#_CPPv4I0DpEN5arrow15VisitTypeInlineE6StatusRK8DataTypeP7VISITORDpRR4ARGS" title="arrow::VisitTypeInline"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">arrow::VisitTypeInline()</span></code></a>. |
| (See more about type visitors in <a class="reference internal" href="../datatypes.html#cpp-visitor-pattern"><span class="std std-ref">Visitor Pattern</span></a>.)</p> |
| <p>At the end of that class is the private method <code class="docutils literal notranslate"><span class="pre">FieldValues()</span></code>, which returns |
| an iterator of the column values for the current field across the rows. In |
| row-based structures that are flat (such as a vector of values) this may be |
| trivial to implement. But if the schema is nested, as in the case of JSON documents, |
| a special iterator is needed to navigate the levels of nesting. See the |
| <a class="reference external" href="https://github.com/apache/arrow/blob/main/cpp/examples/arrow/rapidjson_row_converter.cc">full example</a> |
| for the implementation details of <code class="docutils literal notranslate"><span class="pre">DocValuesIterator</span></code>.</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="linenos">323</span><span class="k">class</span><span class="w"> </span><span class="nc">JsonValueConverter</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">324</span><span class="w"> </span><span class="k">public</span><span class="o">:</span> |
| <span class="linenos">325</span><span class="w"> </span><span class="k">explicit</span><span class="w"> </span><span class="n">JsonValueConverter</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">>&</span><span class="w"> </span><span class="n">rows</span><span class="p">)</span> |
| <span class="linenos">326</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">rows_</span><span class="p">(</span><span class="n">rows</span><span class="p">),</span><span class="w"> </span><span class="n">array_levels_</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{}</span> |
| <span class="linenos">327</span> |
| <span class="linenos">328</span><span class="w"> </span><span class="n">JsonValueConverter</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">>&</span><span class="w"> </span><span class="n">rows</span><span class="p">,</span> |
| <span class="linenos">329</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">>&</span><span class="w"> </span><span class="n">root_path</span><span class="p">,</span><span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">array_levels</span><span class="p">)</span> |
| <span class="linenos">330</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">rows_</span><span class="p">(</span><span class="n">rows</span><span class="p">),</span><span class="w"> </span><span class="n">root_path_</span><span class="p">(</span><span class="n">root_path</span><span class="p">),</span><span class="w"> </span><span class="n">array_levels_</span><span class="p">(</span><span class="n">array_levels</span><span class="p">)</span><span class="w"> </span><span class="p">{}</span> |
| <span class="linenos">331</span> |
| <span class="linenos">332</span><span class="w"> </span><span class="c1">/// \brief For field passed in, append corresponding values to builder</span> |
| <span class="linenos">333</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Convert</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">&</span><span class="w"> </span><span class="n">field</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">334</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">Convert</span><span class="p">(</span><span class="n">field</span><span class="p">,</span><span class="w"> </span><span class="n">field</span><span class="p">.</span><span class="n">name</span><span class="p">(),</span><span class="w"> </span><span class="n">builder</span><span class="p">);</span> |
| <span class="linenos">335</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">336</span> |
| <span class="linenos">337</span><span class="w"> </span><span class="c1">/// \brief For field passed in, append corresponding values to builder</span> |
| <span class="linenos">338</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Convert</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">&</span><span class="w"> </span><span class="n">field</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">&</span><span class="w"> </span><span class="n">field_name</span><span class="p">,</span> |
| <span class="linenos">339</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">340</span><span class="w"> </span><span class="n">field_name_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">field_name</span><span class="p">;</span> |
| <span class="linenos">341</span><span class="w"> </span><span class="n">builder_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">builder</span><span class="p">;</span> |
| <span class="linenos">342</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">arrow</span><span class="o">::</span><span class="n">VisitTypeInline</span><span class="p">(</span><span class="o">*</span><span class="n">field</span><span class="p">.</span><span class="n">type</span><span class="p">().</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="k">this</span><span class="p">));</span> |
| <span class="linenos">343</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">344</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">345</span> |
| <span class="linenos">346</span><span class="w"> </span><span class="c1">// Default implementation</span> |
| <span class="linenos">347</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">DataType</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">348</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">NotImplemented</span><span class="p">(</span> |
| <span class="linenos">349</span><span class="w"> </span><span class="s">"Cannot convert json value to Arrow array of type "</span><span class="p">,</span><span class="w"> </span><span class="n">type</span><span class="p">.</span><span class="n">ToString</span><span class="p">());</span> |
| <span class="linenos">350</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">351</span> |
| <span class="linenos">352</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Type</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">353</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Builder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Builder</span><span class="o">*></span><span class="p">(</span><span class="n">builder_</span><span class="p">);</span> |
| <span class="linenos">354</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">maybe_value</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">FieldValues</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">355</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">maybe_value</span><span class="p">);</span> |
| <span class="linenos">356</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">357</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">AppendNull</span><span class="p">());</span> |
| <span class="linenos">358</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">359</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsUint</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">360</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetUint</span><span class="p">()));</span> |
| <span class="linenos">361</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsInt</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">362</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetInt</span><span class="p">()));</span> |
| <span class="linenos">363</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsUint64</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">364</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetUint64</span><span class="p">()));</span> |
| <span class="linenos">365</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsInt64</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">366</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetInt64</span><span class="p">()));</span> |
| <span class="linenos">367</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">368</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">Invalid</span><span class="p">(</span><span class="s">"Value is not an integer"</span><span class="p">);</span> |
| <span class="linenos">369</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">370</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">371</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">372</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">373</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">374</span> |
| <span class="linenos">375</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">DoubleType</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">376</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">DoubleBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">DoubleBuilder</span><span class="o">*></span><span class="p">(</span><span class="n">builder_</span><span class="p">);</span> |
| <span class="linenos">377</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">maybe_value</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">FieldValues</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">378</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">maybe_value</span><span class="p">);</span> |
| <span class="linenos">379</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">380</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">AppendNull</span><span class="p">());</span> |
| <span class="linenos">381</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">382</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetDouble</span><span class="p">()));</span> |
| <span class="linenos">383</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">384</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">385</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">386</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">387</span> |
| <span class="linenos">388</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StringType</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">389</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StringBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">StringBuilder</span><span class="o">*></span><span class="p">(</span><span class="n">builder_</span><span class="p">);</span> |
| <span class="linenos">390</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">maybe_value</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">FieldValues</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">391</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">maybe_value</span><span class="p">);</span> |
| <span class="linenos">392</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">393</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">AppendNull</span><span class="p">());</span> |
| <span class="linenos">394</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">395</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetString</span><span class="p">()));</span> |
| <span class="linenos">396</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">397</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">398</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">399</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">400</span> |
| <span class="linenos">401</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">BooleanType</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">402</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">BooleanBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">BooleanBuilder</span><span class="o">*></span><span class="p">(</span><span class="n">builder_</span><span class="p">);</span> |
| <span class="linenos">403</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">maybe_value</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">FieldValues</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">404</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">maybe_value</span><span class="p">);</span> |
| <span class="linenos">405</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">406</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">AppendNull</span><span class="p">());</span> |
| <span class="linenos">407</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">408</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="n">value</span><span class="o">-></span><span class="n">GetBool</span><span class="p">()));</span> |
| <span class="linenos">409</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">410</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">411</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">412</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">413</span> |
| <span class="linenos">414</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StructType</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">415</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StructBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">StructBuilder</span><span class="o">*></span><span class="p">(</span><span class="n">builder_</span><span class="p">);</span> |
| <span class="linenos">416</span> |
| <span class="linenos">417</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">child_path</span><span class="p">(</span><span class="n">root_path_</span><span class="p">);</span> |
| <span class="linenos">418</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">field_name_</span><span class="p">.</span><span class="n">size</span><span class="p">()</span><span class="w"> </span><span class="o">></span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">419</span><span class="w"> </span><span class="n">child_path</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">field_name_</span><span class="p">);</span> |
| <span class="linenos">420</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">421</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">child_converter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">JsonValueConverter</span><span class="p">(</span><span class="n">rows_</span><span class="p">,</span><span class="w"> </span><span class="n">child_path</span><span class="p">,</span><span class="w"> </span><span class="n">array_levels_</span><span class="p">);</span> |
| <span class="linenos">422</span> |
| <span class="linenos">423</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">type</span><span class="p">.</span><span class="n">num_fields</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">424</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">></span><span class="w"> </span><span class="n">child_field</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">type</span><span class="p">.</span><span class="n">field</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="linenos">425</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">></span><span class="w"> </span><span class="n">child_builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">builder</span><span class="o">-></span><span class="n">child_builder</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="linenos">426</span> |
| <span class="linenos">427</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span> |
| <span class="linenos">428</span><span class="w"> </span><span class="n">child_converter</span><span class="p">.</span><span class="n">Convert</span><span class="p">(</span><span class="o">*</span><span class="n">child_field</span><span class="p">.</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="n">child_builder</span><span class="p">.</span><span class="n">get</span><span class="p">()));</span> |
| <span class="linenos">429</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">430</span> |
| <span class="linenos">431</span><span class="w"> </span><span class="c1">// Make null bitmap</span> |
| <span class="linenos">432</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">maybe_value</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">FieldValues</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">433</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">maybe_value</span><span class="p">);</span> |
| <span class="linenos">434</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="o">!</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">()));</span> |
| <span class="linenos">435</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">436</span> |
| <span class="linenos">437</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">438</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">439</span> |
| <span class="linenos">440</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ListType</span><span class="o">&</span><span class="w"> </span><span class="n">type</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">441</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ListBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">ListBuilder</span><span class="o">*></span><span class="p">(</span><span class="n">builder_</span><span class="p">);</span> |
| <span class="linenos">442</span> |
| <span class="linenos">443</span><span class="w"> </span><span class="c1">// Values and offsets needs to be interleaved in ListBuilder, so first collect the</span> |
| <span class="linenos">444</span><span class="w"> </span><span class="c1">// values</span> |
| <span class="linenos">445</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">></span><span class="w"> </span><span class="n">tmp_value_builder</span><span class="p">;</span> |
| <span class="linenos">446</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="n">tmp_value_builder</span><span class="p">,</span> |
| <span class="linenos">447</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MakeBuilder</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">value_builder</span><span class="p">()</span><span class="o">-></span><span class="n">type</span><span class="p">()));</span> |
| <span class="linenos">448</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">child_path</span><span class="p">(</span><span class="n">root_path_</span><span class="p">);</span> |
| <span class="linenos">449</span><span class="w"> </span><span class="n">child_path</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">field_name_</span><span class="p">);</span> |
| <span class="linenos">450</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">child_converter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">JsonValueConverter</span><span class="p">(</span><span class="n">rows_</span><span class="p">,</span><span class="w"> </span><span class="n">child_path</span><span class="p">,</span><span class="w"> </span><span class="n">array_levels_</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">);</span> |
| <span class="linenos">451</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span> |
| <span class="linenos">452</span><span class="w"> </span><span class="n">child_converter</span><span class="p">.</span><span class="n">Convert</span><span class="p">(</span><span class="o">*</span><span class="n">type</span><span class="p">.</span><span class="n">value_field</span><span class="p">().</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="s">""</span><span class="p">,</span><span class="w"> </span><span class="n">tmp_value_builder</span><span class="p">.</span><span class="n">get</span><span class="p">()));</span> |
| <span class="linenos">453</span> |
| <span class="linenos">454</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">values_array</span><span class="p">;</span> |
| <span class="linenos">455</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">tmp_value_builder</span><span class="o">-></span><span class="n">Finish</span><span class="p">(</span><span class="o">&</span><span class="n">values_array</span><span class="p">));</span> |
| <span class="linenos">456</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayData</span><span class="o">></span><span class="w"> </span><span class="n">values_data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">values_array</span><span class="o">-></span><span class="n">data</span><span class="p">();</span> |
| <span class="linenos">457</span> |
| <span class="linenos">458</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">value_builder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">builder</span><span class="o">-></span><span class="n">value_builder</span><span class="p">();</span> |
| <span class="linenos">459</span><span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">offset</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span> |
| <span class="linenos">460</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="k">auto</span><span class="o">&</span><span class="w"> </span><span class="n">maybe_value</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">FieldValues</span><span class="p">())</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">461</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">maybe_value</span><span class="p">);</span> |
| <span class="linenos">462</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">builder</span><span class="o">-></span><span class="n">Append</span><span class="p">(</span><span class="o">!</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">()));</span> |
| <span class="linenos">463</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">value</span><span class="o">-></span><span class="n">IsNull</span><span class="p">()</span><span class="w"> </span><span class="o">&&</span><span class="w"> </span><span class="n">value</span><span class="o">-></span><span class="n">Size</span><span class="p">()</span><span class="w"> </span><span class="o">></span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">464</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span> |
| <span class="linenos">465</span><span class="w"> </span><span class="n">value_builder</span><span class="o">-></span><span class="n">AppendArraySlice</span><span class="p">(</span><span class="o">*</span><span class="n">values_data</span><span class="p">.</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="n">offset</span><span class="p">,</span><span class="w"> </span><span class="n">value</span><span class="o">-></span><span class="n">Size</span><span class="p">()));</span> |
| <span class="linenos">466</span><span class="w"> </span><span class="n">offset</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="n">value</span><span class="o">-></span><span class="n">Size</span><span class="p">();</span> |
| <span class="linenos">467</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">468</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">469</span> |
| <span class="linenos">470</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">471</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">472</span> |
| <span class="linenos">473</span><span class="w"> </span><span class="k">private</span><span class="o">:</span> |
| <span class="linenos">474</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">field_name_</span><span class="p">;</span> |
| <span class="linenos">475</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ArrayBuilder</span><span class="o">*</span><span class="w"> </span><span class="n">builder_</span><span class="p">;</span> |
| <span class="linenos">476</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">>&</span><span class="w"> </span><span class="n">rows_</span><span class="p">;</span> |
| <span class="linenos">477</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">root_path_</span><span class="p">;</span> |
| <span class="linenos">478</span><span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">array_levels_</span><span class="p">;</span> |
| <span class="linenos">479</span> |
| <span class="linenos">480</span><span class="w"> </span><span class="c1">/// Return a flattened iterator over values at nested location</span> |
| <span class="linenos">481</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Iterator</span><span class="o"><</span><span class="k">const</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="o">*></span><span class="w"> </span><span class="n">FieldValues</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">482</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">path</span><span class="p">(</span><span class="n">root_path_</span><span class="p">);</span> |
| <span class="linenos">483</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">field_name_</span><span class="p">.</span><span class="n">size</span><span class="p">()</span><span class="w"> </span><span class="o">></span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">484</span><span class="w"> </span><span class="n">path</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">field_name_</span><span class="p">);</span> |
| <span class="linenos">485</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">486</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">iter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">DocValuesIterator</span><span class="p">(</span><span class="n">rows_</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">path</span><span class="p">),</span><span class="w"> </span><span class="n">array_levels_</span><span class="p">);</span> |
| <span class="linenos">487</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">fn</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">[</span><span class="n">iter</span><span class="p">]()</span><span class="w"> </span><span class="k">mutable</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Result</span><span class="o"><</span><span class="k">const</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="o">*></span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">488</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">iter</span><span class="p">.</span><span class="n">Next</span><span class="p">();</span> |
| <span class="linenos">489</span><span class="w"> </span><span class="p">};</span> |
| <span class="linenos">490</span> |
| <span class="linenos">491</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MakeFunctionIterator</span><span class="p">(</span><span class="n">fn</span><span class="p">);</span> |
| <span class="linenos">492</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">493</span><span class="p">};</span><span class="w"> </span><span class="c1">// JsonValueConverter</span> |
| </pre></div> |
| </div> |
| </section> |
| <section id="writing-conversions-from-arrow"> |
| <h3>Writing conversions from Arrow<a class="headerlink" href="#writing-conversions-from-arrow" title="Permalink to this heading">#</a></h3> |
| <p>To convert into rows <em>from</em> Arrow record batches, we’ll process the table in |
| smaller batches, visiting each field of the batch and filling the output rows |
| column-by-column.</p> |
| <p>At the top-level, we define <code class="docutils literal notranslate"><span class="pre">ArrowToDocumentConverter</span></code> that provides the API |
| for converting Arrow batches and tables to rows. In many cases, it’s more optimal |
| to perform conversions to rows in smaller batches, rather than doing the entire |
| table at once. So we define one <code class="docutils literal notranslate"><span class="pre">ConvertToVector</span></code> method to convert a single |
| batch, then in the other conversion method we use <a class="reference internal" href="../api/table.html#_CPPv4N5arrow16TableBatchReaderE" title="arrow::TableBatchReader"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">arrow::TableBatchReader</span></code></a> |
| to iterate over slices of a table. This returns Arrow’s iterator type |
| (<a class="reference internal" href="../api/utilities.html#_CPPv4I0EN5arrow8IteratorE" title="arrow::Iterator"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">arrow::Iterator</span></code></a>) so rows could then be processed either one-at-a-time |
| or be collected into a container.</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="linenos">179</span><span class="k">class</span><span class="w"> </span><span class="nc">ArrowToDocumentConverter</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">180</span><span class="w"> </span><span class="k">public</span><span class="o">:</span> |
| <span class="linenos">181</span><span class="w"> </span><span class="c1">/// Convert a single batch of Arrow data into Documents</span> |
| <span class="linenos">182</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Result</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">>></span><span class="w"> </span><span class="n">ConvertToVector</span><span class="p">(</span> |
| <span class="linenos">183</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatch</span><span class="o">></span><span class="w"> </span><span class="n">batch</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">184</span><span class="w"> </span><span class="n">RowBatchBuilder</span><span class="w"> </span><span class="n">builder</span><span class="p">{</span><span class="n">batch</span><span class="o">-></span><span class="n">num_rows</span><span class="p">()};</span> |
| <span class="linenos">185</span> |
| <span class="linenos">186</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">batch</span><span class="o">-></span><span class="n">num_columns</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">187</span><span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">SetField</span><span class="p">(</span><span class="n">batch</span><span class="o">-></span><span class="n">schema</span><span class="p">()</span><span class="o">-></span><span class="n">field</span><span class="p">(</span><span class="n">i</span><span class="p">).</span><span class="n">get</span><span class="p">());</span> |
| <span class="linenos">188</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">arrow</span><span class="o">::</span><span class="n">VisitArrayInline</span><span class="p">(</span><span class="o">*</span><span class="n">batch</span><span class="o">-></span><span class="n">column</span><span class="p">(</span><span class="n">i</span><span class="p">).</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="o">&</span><span class="n">builder</span><span class="p">));</span> |
| <span class="linenos">189</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">190</span> |
| <span class="linenos">191</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">builder</span><span class="p">).</span><span class="n">Rows</span><span class="p">();</span> |
| <span class="linenos">192</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">193</span> |
| <span class="linenos">194</span><span class="w"> </span><span class="c1">/// Convert an Arrow table into an iterator of Documents</span> |
| <span class="linenos">195</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Iterator</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">></span><span class="w"> </span><span class="n">ConvertToIterator</span><span class="p">(</span> |
| <span class="linenos">196</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Table</span><span class="o">></span><span class="w"> </span><span class="n">table</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">batch_size</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">197</span><span class="w"> </span><span class="c1">// Use TableBatchReader to divide table into smaller batches. The batches</span> |
| <span class="linenos">198</span><span class="w"> </span><span class="c1">// created are zero-copy slices with *at most* `batch_size` rows.</span> |
| <span class="linenos">199</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">batch_reader</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">make_shared</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">TableBatchReader</span><span class="o">></span><span class="p">(</span><span class="o">*</span><span class="n">table</span><span class="p">);</span> |
| <span class="linenos">200</span><span class="w"> </span><span class="n">batch_reader</span><span class="o">-></span><span class="n">set_chunksize</span><span class="p">(</span><span class="n">batch_size</span><span class="p">);</span> |
| <span class="linenos">201</span> |
| <span class="linenos">202</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">read_batch</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">[</span><span class="k">this</span><span class="p">](</span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatch</span><span class="o">>&</span><span class="w"> </span><span class="n">batch</span><span class="p">)</span> |
| <span class="linenos">203</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Result</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Iterator</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">>></span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">204</span><span class="w"> </span><span class="n">ARROW_ASSIGN_OR_RAISE</span><span class="p">(</span><span class="k">auto</span><span class="w"> </span><span class="n">rows</span><span class="p">,</span><span class="w"> </span><span class="n">ConvertToVector</span><span class="p">(</span><span class="n">batch</span><span class="p">));</span> |
| <span class="linenos">205</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MakeVectorIterator</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">rows</span><span class="p">));</span> |
| <span class="linenos">206</span><span class="w"> </span><span class="p">};</span> |
| <span class="linenos">207</span> |
| <span class="linenos">208</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">nested_iter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MakeMaybeMapIterator</span><span class="p">(</span> |
| <span class="linenos">209</span><span class="w"> </span><span class="n">read_batch</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MakeIteratorFromReader</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">batch_reader</span><span class="p">)));</span> |
| <span class="linenos">210</span> |
| <span class="linenos">211</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">MakeFlattenIterator</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">nested_iter</span><span class="p">));</span> |
| <span class="linenos">212</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">213</span><span class="p">};</span><span class="w"> </span><span class="c1">// ArrowToDocumentConverter</span> |
| </pre></div> |
| </div> |
| <p>One level down, the output rows are filled in by <code class="docutils literal notranslate"><span class="pre">RowBatchBuilder</span></code>. |
| The <code class="docutils literal notranslate"><span class="pre">RowBatchBuilder</span></code> implements <code class="docutils literal notranslate"><span class="pre">Visit()</span></code> methods, but to save on code we |
| write a template method for array types that have primitive C equivalents |
| (booleans, integers, and floats) using <code class="docutils literal notranslate"><span class="pre">arrow::enable_if_primitive_ctype</span></code>. |
| See <a class="reference internal" href="../api/utilities.html#type-traits"><span class="std std-ref">Type Traits</span></a> for other type predicates.</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="linenos"> 57</span><span class="k">class</span><span class="w"> </span><span class="nc">RowBatchBuilder</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 58</span><span class="w"> </span><span class="k">public</span><span class="o">:</span> |
| <span class="linenos"> 59</span><span class="w"> </span><span class="k">explicit</span><span class="w"> </span><span class="n">RowBatchBuilder</span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">num_rows</span><span class="p">)</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">field_</span><span class="p">(</span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 60</span><span class="w"> </span><span class="c1">// Reserve all of the space required up-front to avoid unnecessary resizing</span> |
| <span class="linenos"> 61</span><span class="w"> </span><span class="n">rows_</span><span class="p">.</span><span class="n">reserve</span><span class="p">(</span><span class="n">num_rows</span><span class="p">);</span> |
| <span class="linenos"> 62</span> |
| <span class="linenos"> 63</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">num_rows</span><span class="p">;</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 64</span><span class="w"> </span><span class="n">rows_</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="p">());</span> |
| <span class="linenos"> 65</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">SetObject</span><span class="p">();</span> |
| <span class="linenos"> 66</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 67</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 68</span> |
| <span class="linenos"> 69</span><span class="w"> </span><span class="c1">/// \brief Set which field to convert.</span> |
| <span class="linenos"> 70</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="n">SetField</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">*</span><span class="w"> </span><span class="n">field</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">field_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">field</span><span class="p">;</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 71</span> |
| <span class="linenos"> 72</span><span class="w"> </span><span class="c1">/// \brief Retrieve converted rows from builder.</span> |
| <span class="linenos"> 73</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">></span><span class="w"> </span><span class="n">Rows</span><span class="p">()</span><span class="w"> </span><span class="o">&&</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">rows_</span><span class="p">);</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 74</span> |
| <span class="linenos"> 75</span><span class="w"> </span><span class="c1">// Default implementation</span> |
| <span class="linenos"> 76</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">&</span><span class="w"> </span><span class="n">array</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 77</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">NotImplemented</span><span class="p">(</span> |
| <span class="linenos"> 78</span><span class="w"> </span><span class="s">"Cannot convert to json document for array of type "</span><span class="p">,</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">type</span><span class="p">()</span><span class="o">-></span><span class="n">ToString</span><span class="p">());</span> |
| <span class="linenos"> 79</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 80</span> |
| <span class="linenos"> 81</span><span class="w"> </span><span class="c1">// Handles booleans, integers, floats</span> |
| <span class="linenos"> 82</span><span class="w"> </span><span class="k">template</span><span class="w"> </span><span class="o"><</span><span class="k">typename</span><span class="w"> </span><span class="nc">ArrayType</span><span class="p">,</span><span class="w"> </span><span class="k">typename</span><span class="w"> </span><span class="nc">DataClass</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">typename</span><span class="w"> </span><span class="nc">ArrayType</span><span class="o">::</span><span class="n">TypeClass</span><span class="o">></span> |
| <span class="linenos"> 83</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">enable_if_primitive_ctype</span><span class="o"><</span><span class="n">DataClass</span><span class="p">,</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">></span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span> |
| <span class="linenos"> 84</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">ArrayType</span><span class="o">&</span><span class="w"> </span><span class="n">array</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 85</span><span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="k">static_cast</span><span class="o"><</span><span class="kt">int64_t</span><span class="o">></span><span class="p">(</span><span class="n">rows_</span><span class="p">.</span><span class="n">size</span><span class="p">())</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">());</span> |
| <span class="linenos"> 86</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 87</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">array</span><span class="p">.</span><span class="n">IsNull</span><span class="p">(</span><span class="n">i</span><span class="p">))</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 88</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="nf">str_key</span><span class="p">(</span><span class="n">field_</span><span class="o">-></span><span class="n">name</span><span class="p">(),</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos"> 89</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">AddMember</span><span class="p">(</span><span class="n">str_key</span><span class="p">,</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">Value</span><span class="p">(</span><span class="n">i</span><span class="p">),</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos"> 90</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 91</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 92</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos"> 93</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos"> 94</span> |
| <span class="linenos"> 95</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StringArray</span><span class="o">&</span><span class="w"> </span><span class="n">array</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 96</span><span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="k">static_cast</span><span class="o"><</span><span class="kt">int64_t</span><span class="o">></span><span class="p">(</span><span class="n">rows_</span><span class="p">.</span><span class="n">size</span><span class="p">())</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">());</span> |
| <span class="linenos"> 97</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 98</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">array</span><span class="p">.</span><span class="n">IsNull</span><span class="p">(</span><span class="n">i</span><span class="p">))</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos"> 99</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="nf">str_key</span><span class="p">(</span><span class="n">field_</span><span class="o">-></span><span class="n">name</span><span class="p">(),</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos">100</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string_view</span><span class="w"> </span><span class="n">value_view</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">Value</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="linenos">101</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="n">value</span><span class="p">;</span> |
| <span class="linenos">102</span><span class="w"> </span><span class="n">value</span><span class="p">.</span><span class="n">SetString</span><span class="p">(</span><span class="n">value_view</span><span class="p">.</span><span class="n">data</span><span class="p">(),</span> |
| <span class="linenos">103</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">SizeType</span><span class="o">></span><span class="p">(</span><span class="n">value_view</span><span class="p">.</span><span class="n">size</span><span class="p">()),</span> |
| <span class="linenos">104</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos">105</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">AddMember</span><span class="p">(</span><span class="n">str_key</span><span class="p">,</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos">106</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">107</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">108</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">109</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">110</span> |
| <span class="linenos">111</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StructArray</span><span class="o">&</span><span class="w"> </span><span class="n">array</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">112</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">StructType</span><span class="o">*</span><span class="w"> </span><span class="n">type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">struct_type</span><span class="p">();</span> |
| <span class="linenos">113</span> |
| <span class="linenos">114</span><span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="k">static_cast</span><span class="o"><</span><span class="kt">int64_t</span><span class="o">></span><span class="p">(</span><span class="n">rows_</span><span class="p">.</span><span class="n">size</span><span class="p">())</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">());</span> |
| <span class="linenos">115</span> |
| <span class="linenos">116</span><span class="w"> </span><span class="n">RowBatchBuilder</span><span class="w"> </span><span class="nf">child_builder</span><span class="p">(</span><span class="n">rows_</span><span class="p">.</span><span class="n">size</span><span class="p">());</span> |
| <span class="linenos">117</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">type</span><span class="o">-></span><span class="n">num_fields</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">118</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">*</span><span class="w"> </span><span class="n">child_field</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">type</span><span class="o">-></span><span class="n">field</span><span class="p">(</span><span class="n">i</span><span class="p">).</span><span class="n">get</span><span class="p">();</span> |
| <span class="linenos">119</span><span class="w"> </span><span class="n">child_builder</span><span class="p">.</span><span class="n">SetField</span><span class="p">(</span><span class="n">child_field</span><span class="p">);</span> |
| <span class="linenos">120</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">arrow</span><span class="o">::</span><span class="n">VisitArrayInline</span><span class="p">(</span><span class="o">*</span><span class="n">array</span><span class="p">.</span><span class="n">field</span><span class="p">(</span><span class="n">i</span><span class="p">).</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="o">&</span><span class="n">child_builder</span><span class="p">));</span> |
| <span class="linenos">121</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">122</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">></span><span class="w"> </span><span class="n">rows</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">child_builder</span><span class="p">).</span><span class="n">Rows</span><span class="p">();</span> |
| <span class="linenos">123</span> |
| <span class="linenos">124</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">125</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">array</span><span class="p">.</span><span class="n">IsNull</span><span class="p">(</span><span class="n">i</span><span class="p">))</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">126</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="nf">str_key</span><span class="p">(</span><span class="n">field_</span><span class="o">-></span><span class="n">name</span><span class="p">(),</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos">127</span><span class="w"> </span><span class="c1">// Must copy value to new allocator</span> |
| <span class="linenos">128</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="n">row_val</span><span class="p">;</span> |
| <span class="linenos">129</span><span class="w"> </span><span class="n">row_val</span><span class="p">.</span><span class="n">CopyFrom</span><span class="p">(</span><span class="n">rows</span><span class="p">[</span><span class="n">i</span><span class="p">],</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos">130</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">AddMember</span><span class="p">(</span><span class="n">str_key</span><span class="p">,</span><span class="w"> </span><span class="n">row_val</span><span class="p">,</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">());</span> |
| <span class="linenos">131</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">132</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">133</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">134</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">135</span> |
| <span class="linenos">136</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="w"> </span><span class="n">Visit</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ListArray</span><span class="o">&</span><span class="w"> </span><span class="n">array</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">137</span><span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="k">static_cast</span><span class="o"><</span><span class="kt">int64_t</span><span class="o">></span><span class="p">(</span><span class="n">rows_</span><span class="p">.</span><span class="n">size</span><span class="p">())</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">());</span> |
| <span class="linenos">138</span><span class="w"> </span><span class="c1">// First create rows from values</span> |
| <span class="linenos">139</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">values</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">values</span><span class="p">();</span> |
| <span class="linenos">140</span><span class="w"> </span><span class="n">RowBatchBuilder</span><span class="w"> </span><span class="nf">child_builder</span><span class="p">(</span><span class="n">values</span><span class="o">-></span><span class="n">length</span><span class="p">());</span> |
| <span class="linenos">141</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">*</span><span class="w"> </span><span class="n">value_field</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">list_type</span><span class="p">()</span><span class="o">-></span><span class="n">value_field</span><span class="p">().</span><span class="n">get</span><span class="p">();</span> |
| <span class="linenos">142</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">value_field_name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">value_field</span><span class="o">-></span><span class="n">name</span><span class="p">();</span> |
| <span class="linenos">143</span><span class="w"> </span><span class="n">child_builder</span><span class="p">.</span><span class="n">SetField</span><span class="p">(</span><span class="n">value_field</span><span class="p">);</span> |
| <span class="linenos">144</span><span class="w"> </span><span class="n">ARROW_RETURN_NOT_OK</span><span class="p">(</span><span class="n">arrow</span><span class="o">::</span><span class="n">VisitArrayInline</span><span class="p">(</span><span class="o">*</span><span class="n">values</span><span class="p">.</span><span class="n">get</span><span class="p">(),</span><span class="w"> </span><span class="o">&</span><span class="n">child_builder</span><span class="p">));</span> |
| <span class="linenos">145</span> |
| <span class="linenos">146</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">></span><span class="w"> </span><span class="n">rows</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">child_builder</span><span class="p">).</span><span class="n">Rows</span><span class="p">();</span> |
| <span class="linenos">147</span> |
| <span class="linenos">148</span><span class="w"> </span><span class="kt">int64_t</span><span class="w"> </span><span class="n">values_i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span> |
| <span class="linenos">149</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">length</span><span class="p">();</span><span class="w"> </span><span class="o">++</span><span class="n">i</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">150</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">array</span><span class="p">.</span><span class="n">IsNull</span><span class="p">(</span><span class="n">i</span><span class="p">))</span><span class="w"> </span><span class="k">continue</span><span class="p">;</span> |
| <span class="linenos">151</span> |
| <span class="linenos">152</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">::</span><span class="n">AllocatorType</span><span class="o">&</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">GetAllocator</span><span class="p">();</span> |
| <span class="linenos">153</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">array_len</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">array</span><span class="p">.</span><span class="n">value_length</span><span class="p">(</span><span class="n">i</span><span class="p">);</span> |
| <span class="linenos">154</span> |
| <span class="linenos">155</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="n">value</span><span class="p">;</span> |
| <span class="linenos">156</span><span class="w"> </span><span class="n">value</span><span class="p">.</span><span class="n">SetArray</span><span class="p">();</span> |
| <span class="linenos">157</span><span class="w"> </span><span class="n">value</span><span class="p">.</span><span class="n">Reserve</span><span class="p">(</span><span class="n">array_len</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="linenos">158</span> |
| <span class="linenos">159</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int64_t</span><span class="w"> </span><span class="n">j</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">j</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">array_len</span><span class="p">;</span><span class="w"> </span><span class="o">++</span><span class="n">j</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="linenos">160</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="n">row_val</span><span class="p">;</span> |
| <span class="linenos">161</span><span class="w"> </span><span class="c1">// Must copy value to new allocator</span> |
| <span class="linenos">162</span><span class="w"> </span><span class="n">row_val</span><span class="p">.</span><span class="n">CopyFrom</span><span class="p">(</span><span class="n">rows</span><span class="p">[</span><span class="n">values_i</span><span class="p">][</span><span class="n">value_field_name</span><span class="p">],</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="linenos">163</span><span class="w"> </span><span class="n">value</span><span class="p">.</span><span class="n">PushBack</span><span class="p">(</span><span class="n">row_val</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="linenos">164</span><span class="w"> </span><span class="o">++</span><span class="n">values_i</span><span class="p">;</span> |
| <span class="linenos">165</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">166</span> |
| <span class="linenos">167</span><span class="w"> </span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Value</span><span class="w"> </span><span class="n">str_key</span><span class="p">(</span><span class="n">field_</span><span class="o">-></span><span class="n">name</span><span class="p">(),</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="linenos">168</span><span class="w"> </span><span class="n">rows_</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">AddMember</span><span class="p">(</span><span class="n">str_key</span><span class="p">,</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="linenos">169</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">170</span> |
| <span class="linenos">171</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Status</span><span class="o">::</span><span class="n">OK</span><span class="p">();</span> |
| <span class="linenos">172</span><span class="w"> </span><span class="p">}</span> |
| <span class="linenos">173</span> |
| <span class="linenos">174</span><span class="w"> </span><span class="k">private</span><span class="o">:</span> |
| <span class="linenos">175</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Field</span><span class="o">*</span><span class="w"> </span><span class="n">field_</span><span class="p">;</span> |
| <span class="linenos">176</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">rapidjson</span><span class="o">::</span><span class="n">Document</span><span class="o">></span><span class="w"> </span><span class="n">rows_</span><span class="p">;</span> |
| <span class="linenos">177</span><span class="p">};</span><span class="w"> </span><span class="c1">// RowBatchBuilder</span> |
| </pre></div> |
| </div> |
| </section> |
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