javadocAggregate/org/apache/calcite/sql/type/SqlTypeCoercionRule.html - calcite-site - Git at Google

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 <h1 title="Class SqlTypeCoercionRule" class="title">Class SqlTypeCoercionRule</h1>
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 <dd><code><a href="SqlTypeMappingRule.html" title="interface in org.apache.calcite.sql.type">SqlTypeMappingRule</a></code></dd>
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 <hr>
 <pre>public class <span class="typeNameLabel">SqlTypeCoercionRule</span>
 extends <a href="https://docs.oracle.com/javase/9/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang" class="externalLink">Object</a>
 implements <a href="SqlTypeMappingRule.html" title="interface in org.apache.calcite.sql.type">SqlTypeMappingRule</a></pre>
 <div class="block">Rules that determine whether a type is castable from another type.

  <p>These rules specify the conversion matrix with explicit CAST.

  <p>The implicit type coercion matrix should be a sub-set of this explicit one.
  We do not define an implicit type coercion matrix, instead we have specific
  coercion rules for all kinds of SQL contexts which actually define the "matrix".

  <p>To add a new implementation to this class, follow
  these steps:

  <ol>
    <li>Initialize a <a href="SqlTypeMappingRules.Builder.html" title="class in org.apache.calcite.sql.type"><code>SqlTypeMappingRules.Builder</code></a> instance
    with default mappings of <code>INSTANCE</code>.</li>
    <li>Modify the mappings with the Builder.</li>
    <li>Construct a new <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type"><code>SqlTypeCoercionRule</code></a> instance with method
    <a href="#instance(java.util.Map)"><code>instance(Map)</code></a>.</li>
    <li>Set the <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type"><code>SqlTypeCoercionRule</code></a> instance into the
    <a href="../validate/SqlValidator.html" title="interface in org.apache.calcite.sql.validate"><code>SqlValidator</code></a>.</li>
  </ol>

  <p>The code snippet below illustrates how to implement a customized instance.

  <pre>
      // Initialize a Builder instance with the default mappings.
      Builder builder = SqlTypeMappingRules.builder();
      builder.addAll(SqlTypeCoercionRules.instance().getTypeMapping());

      // Do the tweak, for example, if we want to add a rule to allow
      // coerce BOOLEAN to TIMESTAMP.
      builder.add(SqlTypeName.TIMESTAMP,
          builder.copyValues(SqlTypeName.TIMESTAMP)
              .add(SqlTypeName.BOOLEAN).build());

      // Initialize a SqlTypeCoercionRules with the new builder mappings.
      SqlTypeCoercionRules typeCoercionRules = SqlTypeCoercionRules.instance(builder.map);

      // Set the SqlTypeCoercionRules instance into the SqlValidator.
      SqlValidator.Config validatorConf ...;
      validatorConf.withTypeCoercionRules(typeCoercionRules);
      // Use this conf to initialize the SqlValidator.
  </pre></div>
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 <td class="colFirst"><code><a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a>&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,&#8203;com.google.common.collect.ImmutableSet&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>&gt;&gt;</code></td>
 <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#getTypeMapping()">getTypeMapping</a></span>()</code></th>
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 <div class="block">Returns the type mappings of this rule instance.</div>
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 <td class="colFirst"><code>static <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></code></td>
 <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#instance()">instance</a></span>()</code></th>
 <td class="colLast">
 <div class="block">Returns an instance.</div>
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 <td class="colFirst"><code>static <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></code></td>
 <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#instance(java.util.Map)">instance</a></span>&#8203;(<a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a>&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,&#8203;com.google.common.collect.ImmutableSet&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>&gt;&gt;&nbsp;map)</code></th>
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 <div class="block">Returns an instance with specified type mappings.</div>
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 <h3><a id="instance(java.util.Map)">instance</a></h3>
 <div class="memberSignature"><span class="modifiers">public static</span>&nbsp;<span class="returnType"><a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></span>&nbsp;<span class="memberName">instance</span>&#8203;(<span class="arguments"><a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a>&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,&#8203;com.google.common.collect.ImmutableSet&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>&gt;&gt;&nbsp;map)</span></div>
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 <div class="memberSignature"><span class="modifiers">public</span>&nbsp;<span class="returnType"><a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a>&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,&#8203;com.google.common.collect.ImmutableSet&lt;<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>&gt;&gt;</span>&nbsp;<span class="memberName">getTypeMapping</span>()</div>
 <div class="block"><span class="descfrmTypeLabel">Description copied from interface:&nbsp;<code><a href="SqlTypeMappingRule.html#getTypeMapping()">SqlTypeMappingRule</a></code></span></div>
 <div class="block">Returns the type mappings of this rule instance.

  <p>The mappings should be immutable.</div>
 <dl>
 <dt><span class="overrideSpecifyLabel">Specified by:</span></dt>
 <dd><code><a href="SqlTypeMappingRule.html#getTypeMapping()">getTypeMapping</a></code>&nbsp;in interface&nbsp;<code><a href="SqlTypeMappingRule.html" title="interface in org.apache.calcite.sql.type">SqlTypeMappingRule</a></code></dd>
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	<pre>public class <span class="typeNameLabel">SqlTypeCoercionRule</span>
	extends <a href="https://docs.oracle.com/javase/9/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang" class="externalLink">Object</a>
	implements <a href="SqlTypeMappingRule.html" title="interface in org.apache.calcite.sql.type">SqlTypeMappingRule</a></pre>
	<div class="block">Rules that determine whether a type is castable from another type.

	<p>These rules specify the conversion matrix with explicit CAST.

	<p>The implicit type coercion matrix should be a sub-set of this explicit one.
	We do not define an implicit type coercion matrix, instead we have specific
	coercion rules for all kinds of SQL contexts which actually define the "matrix".

	<p>To add a new implementation to this class, follow
	these steps:

	<ol>
	<li>Initialize a <a href="SqlTypeMappingRules.Builder.html" title="class in org.apache.calcite.sql.type"><code>SqlTypeMappingRules.Builder</code></a> instance
	with default mappings of <code>INSTANCE</code>.</li>
	<li>Modify the mappings with the Builder.</li>
	<li>Construct a new <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type"><code>SqlTypeCoercionRule</code></a> instance with method
	<a href="#instance(java.util.Map)"><code>instance(Map)</code></a>.</li>
	<li>Set the <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type"><code>SqlTypeCoercionRule</code></a> instance into the
	<a href="../validate/SqlValidator.html" title="interface in org.apache.calcite.sql.validate"><code>SqlValidator</code></a>.</li>
	</ol>

	<p>The code snippet below illustrates how to implement a customized instance.

	<pre>
	// Initialize a Builder instance with the default mappings.
	Builder builder = SqlTypeMappingRules.builder();
	builder.addAll(SqlTypeCoercionRules.instance().getTypeMapping());

	// Do the tweak, for example, if we want to add a rule to allow
	// coerce BOOLEAN to TIMESTAMP.
	builder.add(SqlTypeName.TIMESTAMP,
	builder.copyValues(SqlTypeName.TIMESTAMP)
	.add(SqlTypeName.BOOLEAN).build());

	// Initialize a SqlTypeCoercionRules with the new builder mappings.
	SqlTypeCoercionRules typeCoercionRules = SqlTypeCoercionRules.instance(builder.map);

	// Set the SqlTypeCoercionRules instance into the SqlValidator.
	SqlValidator.Config validatorConf ...;
	validatorConf.withTypeCoercionRules(typeCoercionRules);
	// Use this conf to initialize the SqlValidator.
	</pre></div>
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	<th class="colLast" scope="col">Description</th>
	</tr>
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	<tr class="altColor">
	<td class="colFirst"><code>static <a href="https://docs.oracle.com/javase/9/docs/api/java/lang/ThreadLocal.html?is-external=true" title="class or interface in java.lang" class="externalLink">ThreadLocal</a><<a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a>></code></td>
	<th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#THREAD_PROVIDERS">THREAD_PROVIDERS</a></span></code></th>
	<td class="colLast"> </td>
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	<table aria-labelledby="t0">
	<thead>
	<tr>
	<th class="colFirst" scope="col">Modifier and Type</th>
	<th class="colSecond" scope="col">Method</th>
	<th class="colLast" scope="col">Description</th>
	</tr>
	</thead>
	<tbody>
	<tr class="altColor" id="i0">
	<td class="colFirst"><code><a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a><<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,com.google.common.collect.ImmutableSet<<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>>></code></td>
	<th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#getTypeMapping()">getTypeMapping</a></span>()</code></th>
	<td class="colLast">
	<div class="block">Returns the type mappings of this rule instance.</div>
	</td>
	</tr>
	<tr class="rowColor" id="i1">
	<td class="colFirst"><code>static <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></code></td>
	<th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#instance()">instance</a></span>()</code></th>
	<td class="colLast">
	<div class="block">Returns an instance.</div>
	</td>
	</tr>
	<tr class="altColor" id="i2">
	<td class="colFirst"><code>static <a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></code></td>
	<th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#instance(java.util.Map)">instance</a></span>(<a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a><<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,com.google.common.collect.ImmutableSet<<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>>> map)</code></th>
	<td class="colLast">
	<div class="block">Returns an instance with specified type mappings.</div>
	</td>
	</tr>
	</tbody>
	</table>
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	<h3>Methods inherited from class java.lang.<a href="https://docs.oracle.com/javase/9/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang" class="externalLink">Object</a></h3>
	<a id="methods.inherited.from.class.java.lang.Object">
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	<div class="inheritedList">
	<h3>Methods inherited from interface org.apache.calcite.sql.type.<a href="SqlTypeMappingRule.html" title="interface in org.apache.calcite.sql.type">SqlTypeMappingRule</a></h3>
	<a id="methods.inherited.from.class.org.apache.calcite.sql.type.SqlTypeMappingRule">
	<!-- -->
	</a><code><a href="SqlTypeMappingRule.html#canApplyFrom(org.apache.calcite.sql.type.SqlTypeName,org.apache.calcite.sql.type.SqlTypeName)">canApplyFrom</a></code></div>
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	<h3><a id="THREAD_PROVIDERS">THREAD_PROVIDERS</a></h3>
	<div class="memberSignature"><span class="modifiers">public static final</span> <span class="returnType"><a href="https://docs.oracle.com/javase/9/docs/api/java/lang/ThreadLocal.html?is-external=true" title="class or interface in java.lang" class="externalLink">ThreadLocal</a><<a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a>></span> <span class="memberName">THREAD_PROVIDERS</span></div>
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	<div class="memberSignature"><span class="modifiers">public static</span> <span class="returnType"><a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></span> <span class="memberName">instance</span>()</div>
	<div class="block">Returns an instance.</div>
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	<h3><a id="instance(java.util.Map)">instance</a></h3>
	<div class="memberSignature"><span class="modifiers">public static</span> <span class="returnType"><a href="SqlTypeCoercionRule.html" title="class in org.apache.calcite.sql.type">SqlTypeCoercionRule</a></span> <span class="memberName">instance</span>(<span class="arguments"><a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a><<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,com.google.common.collect.ImmutableSet<<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>>> map)</span></div>
	<div class="block">Returns an instance with specified type mappings.</div>
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	<h3><a id="getTypeMapping()">getTypeMapping</a></h3>
	<div class="memberSignature"><span class="modifiers">public</span> <span class="returnType"><a href="https://docs.oracle.com/javase/9/docs/api/java/util/Map.html?is-external=true" title="class or interface in java.util" class="externalLink">Map</a><<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>,com.google.common.collect.ImmutableSet<<a href="SqlTypeName.html" title="enum in org.apache.calcite.sql.type">SqlTypeName</a>>></span> <span class="memberName">getTypeMapping</span>()</div>
	<div class="block"><span class="descfrmTypeLabel">Description copied from interface: <code><a href="SqlTypeMappingRule.html#getTypeMapping()">SqlTypeMappingRule</a></code></span></div>
	<div class="block">Returns the type mappings of this rule instance.

	<p>The mappings should be immutable.</div>
	<dl>
	<dt><span class="overrideSpecifyLabel">Specified by:</span></dt>
	<dd><code><a href="SqlTypeMappingRule.html#getTypeMapping()">getTypeMapping</a></code> in interface <code><a href="SqlTypeMappingRule.html" title="interface in org.apache.calcite.sql.type">SqlTypeMappingRule</a></code></dd>
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