yjhjstz commented on code in PR #1764:
URL: https://github.com/apache/cloudberry/pull/1764#discussion_r3299519803
##########
src/backend/gporca/libgpopt/src/xforms/CXformLeftSemiJoin2InnerJoin.cpp:
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@@ -63,6 +68,16 @@
CXformLeftSemiJoin2InnerJoin::CXformLeftSemiJoin2InnerJoin(CMemoryPool *mp)
CXform::EXformPromise
CXformLeftSemiJoin2InnerJoin::Exfp(CExpressionHandle &exprhdl) const
{
+ /*
+ * In parallel mode, prefer direct semi-join implementations. Rewriting
a
+ * semi-join to an inner join plus dedup can produce unstable ORCA plans
+ * for parallel queries.
+ */
+ if (gpdb::IsParallelModeOK())
+ {
+ return ExfpNone;
Review Comment:
Disabling them removes a plan candidate that may have been the cost-optimal
choice even for some serial queries in a parallel-enabled session, we need to
find root cause .
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