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| <div class="subTitle">org.apache.drill.exec.vector.accessor</div> |
| <h2 title="Interface VariantReader" class="title">Interface VariantReader</h2> |
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| <dl> |
| <dt>All Superinterfaces:</dt> |
| <dd><a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html" title="interface in org.apache.drill.exec.vector.accessor">ColumnReader</a></dd> |
| </dl> |
| <dl> |
| <dt>All Known Implementing Classes:</dt> |
| <dd><a href="../../../../../../org/apache/drill/exec/vector/accessor/reader/UnionReaderImpl.html" title="class in org.apache.drill.exec.vector.accessor.reader">UnionReaderImpl</a></dd> |
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| <hr> |
| <br> |
| <pre>public interface <span class="typeNameLabel">VariantReader</span> |
| extends <a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html" title="interface in org.apache.drill.exec.vector.accessor">ColumnReader</a></pre> |
| <div class="block">Reader for a Drill "union vector." The union vector is presented |
| as a reader over a set of variants. In the old Visual Basic world, |
| "the Variant data type is a tagged union that can be used to |
| represent any other data type." The term is used here to avoid |
| confusion with the "union operator" which is something entirely |
| different. |
| <p> |
| At read time, the set of possible types is fixed. A request to |
| obtain a reader for an unused type returns a null pointer. |
| <p> |
| This reader is essentially a map of types: it allows access to |
| type-specific readers for the set of types supported in the |
| current vector. A client checks the type of each value, then |
| uses the proper type-specific reader to access that value.</div> |
| <dl> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><code>VariantWriter}</code></dd> |
| </dl> |
| </li> |
| </ul> |
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| <div class="summary"> |
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| <h3>Method Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> |
| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t2" class="tableTab"><span><a href="javascript:show(2);">Instance Methods</a></span><span class="tabEnd"> </span></span><span id="t3" class="tableTab"><span><a href="javascript:show(4);">Abstract Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/vector/accessor/ArrayReader.html" title="interface in org.apache.drill.exec.vector.accessor">ArrayReader</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#array--">array</a></span>()</code> </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#dataType--">dataType</a></span>()</code> |
| <div class="block">Return the data type of the current value.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#hasType-org.apache.drill.common.types.TypeProtos.MinorType-">hasType</a></span>(<a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> type)</code> |
| <div class="block">Determine if a given type is supported by the union vector |
| for some value in the result set.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/vector/accessor/ObjectReader.html" title="interface in org.apache.drill.exec.vector.accessor">ObjectReader</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#member--">member</a></span>()</code> |
| <div class="block">Return the reader for the member type of the current row.</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/vector/accessor/ObjectReader.html" title="interface in org.apache.drill.exec.vector.accessor">ObjectReader</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#member-org.apache.drill.common.types.TypeProtos.MinorType-">member</a></span>(<a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> type)</code> |
| <div class="block">Return the member reader for the given type.</div> |
| </td> |
| </tr> |
| <tr id="i5" class="rowColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/vector/accessor/ScalarReader.html" title="interface in org.apache.drill.exec.vector.accessor">ScalarReader</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#scalar--">scalar</a></span>()</code> |
| <div class="block">Return the appropriate scalar reader for the current value.</div> |
| </td> |
| </tr> |
| <tr id="i6" class="altColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/vector/accessor/ScalarReader.html" title="interface in org.apache.drill.exec.vector.accessor">ScalarReader</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#scalar-org.apache.drill.common.types.TypeProtos.MinorType-">scalar</a></span>(<a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> type)</code> |
| <div class="block">Return the scalar reader for the given type member.</div> |
| </td> |
| </tr> |
| <tr id="i7" class="rowColor"> |
| <td class="colFirst"><code>int</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#size--">size</a></span>()</code> </td> |
| </tr> |
| <tr id="i8" class="altColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/vector/accessor/TupleReader.html" title="interface in org.apache.drill.exec.vector.accessor">TupleReader</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#tuple--">tuple</a></span>()</code> </td> |
| </tr> |
| <tr id="i9" class="rowColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/drill/exec/record/metadata/VariantMetadata.html" title="interface in org.apache.drill.exec.record.metadata">VariantMetadata</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#variantSchema--">variantSchema</a></span>()</code> </td> |
| </tr> |
| </table> |
| <ul class="blockList"> |
| <li class="blockList"><a name="methods.inherited.from.class.org.apache.drill.exec.vector.accessor.ColumnReader"> |
| <!-- --> |
| </a> |
| <h3>Methods inherited from interface org.apache.drill.exec.vector.accessor.<a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html" title="interface in org.apache.drill.exec.vector.accessor">ColumnReader</a></h3> |
| <code><a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html#getAsString--">getAsString</a>, <a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html#getObject--">getObject</a>, <a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html#isNull--">isNull</a>, <a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html#schema--">schema</a>, <a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html#type--">type</a></code></li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| <div class="details"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ============ METHOD DETAIL ========== --> |
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| <li class="blockList"><a name="method.detail"> |
| <!-- --> |
| </a> |
| <h3>Method Detail</h3> |
| <a name="variantSchema--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>variantSchema</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/record/metadata/VariantMetadata.html" title="interface in org.apache.drill.exec.record.metadata">VariantMetadata</a> variantSchema()</pre> |
| </li> |
| </ul> |
| <a name="size--"> |
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| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>size</h4> |
| <pre>int size()</pre> |
| </li> |
| </ul> |
| <a name="hasType-org.apache.drill.common.types.TypeProtos.MinorType-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>hasType</h4> |
| <pre>boolean hasType(<a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> type)</pre> |
| <div class="block">Determine if a given type is supported by the union vector |
| for some value in the result set.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>type</code> - the Drill minor type to query</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd><tt>true</tt> if a reader for the given type is available, |
| <tt>false</tt> if a request for a reader of that type will return |
| <tt>null</tt>.</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="member-org.apache.drill.common.types.TypeProtos.MinorType-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>member</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/vector/accessor/ObjectReader.html" title="interface in org.apache.drill.exec.vector.accessor">ObjectReader</a> member(<a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> type)</pre> |
| <div class="block">Return the member reader for the given type. The type must be a member |
| of the union. Allows caching readers across rows.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>type</code> - member type</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>reader for that type</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="scalar-org.apache.drill.common.types.TypeProtos.MinorType-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>scalar</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/vector/accessor/ScalarReader.html" title="interface in org.apache.drill.exec.vector.accessor">ScalarReader</a> scalar(<a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> type)</pre> |
| <div class="block">Return the scalar reader for the given type member. The type must be a |
| member of the union. Allows caching readers across rows. Identical to:<br> |
| <tt>>member(type).scalar()</tt></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>type</code> - member type</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>scalar reader for that type</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="dataType--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>dataType</h4> |
| <pre><a href="../../../../../../org/apache/drill/common/types/TypeProtos.MinorType.html" title="enum in org.apache.drill.common.types">TypeProtos.MinorType</a> dataType()</pre> |
| <div class="block">Return the data type of the current value. (What happens if the row is |
| null, must it be a null of some type?)</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>data type of the current data value</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="member--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>member</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/vector/accessor/ObjectReader.html" title="interface in org.apache.drill.exec.vector.accessor">ObjectReader</a> member()</pre> |
| <div class="block">Return the reader for the member type of the current row. |
| Same as:<br/> |
| <tt>member(dataType())</tt></div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>reader for the member type of the current row.</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="scalar--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>scalar</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/vector/accessor/ScalarReader.html" title="interface in org.apache.drill.exec.vector.accessor">ScalarReader</a> scalar()</pre> |
| <div class="block">Return the appropriate scalar reader for the current value.</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd><tt>null</tt> if <a href="../../../../../../org/apache/drill/exec/vector/accessor/ColumnReader.html#isNull--"><code>ColumnReader.isNull()</code></a> returns <tt>true</tt>, |
| else the equivalent of <code>scalar</code>( |
| <a href="../../../../../../org/apache/drill/exec/vector/accessor/VariantReader.html#dataType--"><code>dataType()</code></a> )</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/IllegalStateException.html?is-external=true" title="class or interface in java.lang">IllegalStateException</a></code> - if called for a variant that |
| holds a tuple or an array</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="tuple--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>tuple</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/vector/accessor/TupleReader.html" title="interface in org.apache.drill.exec.vector.accessor">TupleReader</a> tuple()</pre> |
| </li> |
| </ul> |
| <a name="array--"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
| <li class="blockList"> |
| <h4>array</h4> |
| <pre><a href="../../../../../../org/apache/drill/exec/vector/accessor/ArrayReader.html" title="interface in org.apache.drill.exec.vector.accessor">ArrayReader</a> array()</pre> |
| </li> |
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