org.apache.drill.exec.planner.logical

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.

Field Summary

Fields

Modifier and Type	Field and Description
static org.apache.calcite.plan.RelOptRule	AGG_ON_PROJ_ON_SCAN
static org.apache.calcite.plan.RelOptRule	AGG_ON_SCAN

Fields inherited from class org.apache.calcite.plan.RelOptRule

description, operands, relBuilderFactory

Method Summary

Modifier and Type	Method and Description
void	onMatch(org.apache.calcite.plan.RelOptRuleCall call)

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

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

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

Method Detail

onMatch

public void onMatch(org.apache.calcite.plan.RelOptRuleCall call)

Specified by:

onMatch in class org.apache.calcite.plan.RelOptRule