org.apache.drill.exec.planner.physical

Class ConvertCountToDirectScan

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.drill.exec.planner.physical.Prule

org.apache.drill.exec.planner.physical.ConvertCountToDirectScan

public class ConvertCountToDirectScan
extends Prule

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 "

Currently, only parquet group scan has the exact row count and column value count, obtained from parquet row group info. This will save the cost to scan the whole parquet files.

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

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ConvertCountToDirectScan(org.apache.calcite.plan.RelOptRuleOperand rule, String id) Creates a SplunkPushDownRule.

Method Summary

Methods

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

Methods inherited from class org.apache.drill.exec.planner.physical.Prule

convert, isSingleMode

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

any, convert, convertList, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, 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

Constructor Detail

ConvertCountToDirectScan

protected ConvertCountToDirectScan(org.apache.calcite.plan.RelOptRuleOperand rule,
                        String id)

Creates a SplunkPushDownRule.

Method Detail

onMatch

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

Specified by:

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