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https://issues.apache.org/jira/browse/CALCITE-1507?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15727202#comment-15727202
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Julian Hyde commented on CALCITE-1507:
--------------------------------------
+1 looks good; thanks for your diligence updating all those tests.
In {{RelOptRulesTest}}, rather than {{checkPlanning}} can you please use the
fluid API if possible, as it makes tests easier to maintain/extend. Something
like this:
{code}
sql(sql)
.withPre(preProgram)
.with(program)
.checkUnchanged();
{code}
> OFFSET cannot be pushed through a JOIN if the non-preserved side of outer
> join is not count-preserving
> ------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-1507
> URL: https://issues.apache.org/jira/browse/CALCITE-1507
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.10.0
> Reporter: Maryann Xue
> Assignee: Maryann Xue
> Priority: Minor
>
> If the non-preserved side of the outer join is not count-preserving, for each
> row from the preserved side, there can be zero, one or multiple matches from
> the non-preserved side, which means the join can produce one or multiple
> rows. So it is safe to push a LIMIT through, but it is invalid to push an
> OFFSET through.
> Take this query as an example:
> {code}
> select d.deptno, empno
> from sales.dept d
> left join sales.emp e using (deptno)
> order by d.deptno offset 1
> {code}
> And rows from "dept" and "emp" tables are like:
> {code}
> "dept"
> deptno
> 10
> 20
> 30
> "emp"
> empno deptno
> 101 10
> 102 10
> 105 30
> {code}
> The expected output is:
> {code}
> d.deptno e.empno
> 10 102
> 20 null
> 30 105
> {code}
> While after applying SortJoinTransposeRule, the rel becomes:
> {code}
> LogicalProject(DEPTNO=[$0], EMPNO=[$2])
> LogicalSort(sort0=[$0], dir0=[ASC], offset=[1])
> LogicalJoin(condition=[=($0, $9)], joinType=[left])
> LogicalSort(sort0=[$0], dir0=[ASC], offset=[1])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> And the output will now be:
> {code}
> d.deptno e.empno
> 20 null
> 30 105
> {code}
> because deptno "10" has been skipped from the left relation by the pushed
> through Sort node.
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