Class ConvertCountToDirectScanRule
java.lang.Object
org.apache.calcite.plan.RelOptRule
org.apache.drill.exec.planner.logical.ConvertCountToDirectScanRule
public class ConvertCountToDirectScanRule
extends org.apache.calcite.plan.RelOptRule
This rule is a logical planning counterpart to a corresponding ConvertCountToDirectScanPrule physical rule
This rule will convert " select count(*) as mycount from table " or " select count(not-nullable-expr) as mycount from table " into
Project(mycount) \ DirectGroupScan ( PojoRecordReader ( rowCount ))or " select count(column) as mycount from table " into
Project(mycount) \ DirectGroupScan (PojoRecordReader (columnValueCount))Rule can be applied if query contains multiple count expressions. " select count(column1), count(column2), count(*) from table "
The rule utilizes the Parquet Metadata Cache's summary information to retrieve the total row count and the per-column null count. As such, the rule is only applicable for Parquet tables and only if the metadata cache has been created with the summary information.
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.calcite.plan.RelOptRule
org.apache.calcite.plan.RelOptRule.ConverterRelOptRuleOperand
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Field Summary
Modifier and TypeFieldDescriptionstatic final org.apache.calcite.plan.RelOptRule
static final org.apache.calcite.plan.RelOptRule
Fields inherited from class org.apache.calcite.plan.RelOptRule
description, operands, relBuilderFactory
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Method Summary
Methods inherited from class org.apache.calcite.plan.RelOptRule
any, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, operandJ, operandJ, some, toString, unordered
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Field Details
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AGG_ON_PROJ_ON_SCAN
public static final org.apache.calcite.plan.RelOptRule AGG_ON_PROJ_ON_SCAN -
AGG_ON_SCAN
public static final org.apache.calcite.plan.RelOptRule AGG_ON_SCAN
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Method Details
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onMatch
public void onMatch(org.apache.calcite.plan.RelOptRuleCall call) - Specified by:
onMatch
in classorg.apache.calcite.plan.RelOptRule
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