pgsql: Fix thinko in join removal.

Fix thinko in join removal.

In commit 9df8f903e I (tgl) switched join_is_removable() from
using the min relid sets of the join under consideration to
using its full syntactic relid sets.  This was a mistake,
as it allowed join removal in cases where a reference to the
join output would survive in some syntactically-lower join
condition.  Revert to the former coding.

Richard Guo

Discussion: https://postgr.es/m/CAMbWs4-EU9uBGSP7G-iTwLBhRQ=rnZKvFDhD+n+xhajokyPCKg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d0f952691ff532aa0c54e9d146fac8d590596646

Modified Files
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src/backend/optimizer/plan/analyzejoins.c | 11 ++++-------
src/test/regress/expected/join.out        | 16 ++++++++++++++++
src/test/regress/sql/join.sql             |  5 +++++
3 files changed, 25 insertions(+), 7 deletions(-)