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Posted to issues@calcite.apache.org by "Volodymyr Vysotskyi (JIRA)" <ji...@apache.org> on 2018/10/25 13:36:00 UTC
[jira] [Resolved] (CALCITE-2158) SubQuery with EXISTS clause
creates redundant aggregate call
[ https://issues.apache.org/jira/browse/CALCITE-2158?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Volodymyr Vysotskyi resolved CALCITE-2158.
------------------------------------------
Resolution: Won't Fix
Fix Version/s: 1.18.0
> SubQuery with EXISTS clause creates redundant aggregate call
> ------------------------------------------------------------
>
> Key: CALCITE-2158
> URL: https://issues.apache.org/jira/browse/CALCITE-2158
> Project: Calcite
> Issue Type: Bug
> Reporter: Volodymyr Vysotskyi
> Assignee: Julian Hyde
> Priority: Major
> Fix For: 1.18.0
>
>
> When {{SqlToRelConverter.Config.isExpand()}} returns true, subqueries are expanded in {{SqlToRelConverter}}.
> Then for the queries, like this:
> {code:sql}
> SELECT cs1.sal
> FROM emp cs1
> WHERE EXISTS
> (SELECT *
> FROM emp cs2
> WHERE cs1.sal = cs2.sal
> AND cs1.deptno <> cs2.deptno)
> {code}
> Calcite returns logical plan with excessive aggregate calls:
> {noformat}
> LogicalProject(SAL=[$5])
> LogicalFilter(condition=[IS NOT NULL($9)])
> LogicalCorrelate(correlation=[$cor0], joinType=[left], requiredColumns=[{5, 7}])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> LogicalAggregate(group=[{}], agg#0=[MIN($0)])
> LogicalProject($f0=[true])
> LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
> LogicalFilter(condition=[AND(=($cor0.SAL, $5), <>($cor0.DEPTNO, $7))])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {noformat}
> But when {{SqlToRelConverter.Config.isExpand()}} returns false and SubQueryRemoveRule rules are applied to the logical plan with RexSubQuery, the resulting logical plan is correct and does not contain excessive aggregate calls:
> {noformat}
> LogicalProject(SAL=[$5])
> LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
> LogicalCorrelate(correlation=[$cor0], joinType=[inner], requiredColumns=[{5, 7}])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> LogicalAggregate(group=[{0}])
> LogicalProject(i=[true])
> LogicalFilter(condition=[AND(=($cor0.SAL, $5), <>($cor0.DEPTNO, $7))])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {noformat}
> These cases may be observed using this unit test:
> {code:java}
> @Test public void testExistsExpand() {
> final HepProgram preProgram = HepProgram.builder()
> .addRuleInstance(SubQueryRemoveRule.FILTER)
> .addRuleInstance(SubQueryRemoveRule.PROJECT)
> .addRuleInstance(SubQueryRemoveRule.JOIN)
> .build();
> final HepProgram program = HepProgram.builder()
> .build();
> final String sql = "SELECT cs1.sal\n"
> + "FROM emp cs1 \n"
> + "WHERE EXISTS\n"
> + "(SELECT *\n"
> + "FROM emp cs2\n"
> + "WHERE cs1.sal = cs2.sal\n"
> + "AND cs1.deptno <> cs2.deptno)";
> sql(sql)
> .withDecorrelation(false)
> .withTrim(false)
> .expand(true) // change to false
> .withPre(preProgram)
> .with(program)
> .checkUnchanged();
> }
> {code}
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