Make reduce_outer_joins() smarter about semijoins. reduce_outer_joins() mistakenly treated a semijoin like a left join for purposes of deciding whether not-null constraints created by the join's quals could be passed down into the join's left-hand side (possibly resulting in outer-join simplification there). Actually, semijoin works like inner join for this purpose, ie, we do not need to see any rows that can't possibly satisfy the quals. Hence, two-line fix to treat semi and inner joins alike. Per observation by Andres Freund about a performance gripe from Yazan Suleiman.
Back-patch to 8.4, since this oversight has been there since the current handling of semijoins was implemented. Branch ------ master Details ------- http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=9688c4e6f1516d2fc0db5d200112c4d91538878d Modified Files -------------- src/backend/optimizer/prep/prepjointree.c | 11 ++++++++--- 1 files changed, 8 insertions(+), 3 deletions(-) -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
