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| <li>Summary: </li> |
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| <div class="sub-title"><span class="package-label-in-type">Package</span> <a href="package-summary.html">org.apache.datafusion</a></div> |
| <h1 title="Interface TableProvider" class="title">Interface TableProvider</h1> |
| </div> |
| <section class="class-description" id="class-description"> |
| <dl class="notes"> |
| <dt>All Known Implementing Classes:</dt> |
| <dd><code><a href="SimpleTableProvider.html" title="class in org.apache.datafusion">SimpleTableProvider</a></code></dd> |
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| <div class="type-signature"><span class="modifiers">public interface </span><span class="element-name type-name-label">TableProvider</span></div> |
| <div class="block">A Java-implemented table that can be registered with a <a href="SessionContext.html" title="class in org.apache.datafusion"><code>SessionContext</code></a> via <a href="SessionContext.html#registerTable(java.lang.String,org.apache.datafusion.TableProvider)"><code>SessionContext.registerTable(String, TableProvider)</code></a>. Mirrors the role of DataFusion's Rust |
| <code>TableProvider</code> trait, but at present only exposes the methods needed for a full table |
| scan; future versions may add filter/projection pushdown and multi-partition support as default |
| methods so existing implementations keep working. |
| |
| <p><a href="SimpleTableProvider.html" title="class in org.apache.datafusion"><code>SimpleTableProvider</code></a> is a ready-made implementation for the common case of "I have a |
| schema and a function that returns an <code>ArrowReader</code>". |
| |
| <p>Each call to <a href="#scan(org.apache.arrow.memory.BufferAllocator)"><code>scan(BufferAllocator)</code></a> must return a fresh, independent <code>ArrowReader</code> so that queries which touch the table more than once (self-joins, <code>UNION ALL</code>, |
| repeated reads) work correctly. The returned reader is closed by the framework when the stream |
| ends. |
| |
| <p>The schema returned by <a href="#schema()"><code>schema()</code></a> is captured once at registration time. Every batch |
| produced by every <code>ArrowReader</code> returned from <a href="#scan(org.apache.arrow.memory.BufferAllocator)"><code>scan(BufferAllocator)</code></a> must conform |
| to it; a mismatch fails the query.</div> |
| </section> |
| <section class="summary"> |
| <ul class="summary-list"> |
| <!-- ========== METHOD SUMMARY =========== --> |
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| <section class="method-summary" id="method-summary"> |
| <h2>Method Summary</h2> |
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| <div class="summary-table three-column-summary"> |
| <div class="table-header col-first">Modifier and Type</div> |
| <div class="table-header col-second">Method</div> |
| <div class="table-header col-last">Description</div> |
| <div class="col-first even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code>org.apache.arrow.vector.ipc.ArrowReader</code></div> |
| <div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#scan(org.apache.arrow.memory.BufferAllocator)" class="member-name-link">scan</a><wbr>(org.apache.arrow.memory.BufferAllocator allocator)</code></div> |
| <div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"> |
| <div class="block">Open a fresh batch stream for this table.</div> |
| </div> |
| <div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code>org.apache.arrow.vector.types.pojo.Schema</code></div> |
| <div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#schema()" class="member-name-link">schema</a>()</code></div> |
| <div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"> |
| <div class="block">The fixed schema of this table.</div> |
| </div> |
| </div> |
| </div> |
| </div> |
| </section> |
| </li> |
| </ul> |
| </section> |
| <section class="details"> |
| <ul class="details-list"> |
| <!-- ============ METHOD DETAIL ========== --> |
| <li> |
| <section class="method-details" id="method-detail"> |
| <h2>Method Details</h2> |
| <ul class="member-list"> |
| <li> |
| <section class="detail" id="schema()"> |
| <h3>schema</h3> |
| <div class="member-signature"><span class="return-type">org.apache.arrow.vector.types.pojo.Schema</span> <span class="element-name">schema</span>()</div> |
| <div class="block">The fixed schema of this table. Called once, at registration time.</div> |
| </section> |
| </li> |
| <li> |
| <section class="detail" id="scan(org.apache.arrow.memory.BufferAllocator)"> |
| <h3>scan</h3> |
| <div class="member-signature"><span class="return-type">org.apache.arrow.vector.ipc.ArrowReader</span> <span class="element-name">scan</span><wbr><span class="parameters">(org.apache.arrow.memory.BufferAllocator allocator)</span></div> |
| <div class="block">Open a fresh batch stream for this table. Called once per physical scan of the table — a single |
| query may invoke this more than once (self-joins, <code>UNION ALL</code> over the same table, etc.). |
| |
| <p>Each invocation MUST return an independent <code>ArrowReader</code>. The reader's schema MUST |
| equal <a href="#schema()"><code>schema()</code></a>. The reader's buffers MUST be allocated from <code>allocator</code> (or from |
| a child of it) — the framework needs the reader's allocator hierarchy to share a root with the |
| one it passes here. The allocator contract mirrors the one on <a href="ScalarFunction.html#evaluate(org.apache.arrow.memory.BufferAllocator,org.apache.datafusion.ScalarFunctionArgs)"><code>ScalarFunction.evaluate(org.apache.arrow.memory.BufferAllocator, org.apache.datafusion.ScalarFunctionArgs)</code></a>.</div> |
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