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| author | Robert Haas <rhaas@postgresql.org> | 2017-03-24 12:30:39 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2017-03-24 12:30:39 -0400 |
| commit | f120b614e070aed39586d1443193738a149a90d4 (patch) | |
| tree | 2ddcc2f4ecd1a04819bdf4d0448321c8e72a5eba /src/backend/utils/cache/syscache.c | |
| parent | 857ee8e391ff6654ef9dcc5dd8b658d7709d0a3c (diff) | |
| download | postgresql-f120b614e070aed39586d1443193738a149a90d4.tar.gz postgresql-f120b614e070aed39586d1443193738a149a90d4.zip | |
plpgsql: Don't generate parallel plans for RETURN QUERY.
Commit 7aea8e4f2daa4b39ca9d1309a0c4aadb0f7ed81b allowed a parallel
plan to be generated when for a RETURN QUERY or RETURN QUERY EXECUTE
statement in a PL/pgsql block, but that's a bad idea because plplgsql
asks the executor for 50 rows at a time. That means that we'll always
be running serially a plan that was intended for parallel execution,
which is not a good idea. Fix by not requesting a parallel plan from
the outset.
Per discussion, back-patch to 9.6. There is a slight risk that, due
to optimizer error, somebody could have a case where the parallel plan
executed serially is actually faster than the supposedly-best serial
plan, but the consensus seems to be that that's not sufficient
justification for leaving 9.6 unpatched.
Discussion: http://postgr.es/m/CA+TgmoZ_ZuH+auEeeWnmtorPsgc_SmP+XWbDsJ+cWvWBSjNwDQ@mail.gmail.com
Discussion: http://postgr.es/m/CA+TgmobXEhvHbJtWDuPZM9bVSLiTj-kShxQJ2uM5GPDze9fRYA@mail.gmail.com
Diffstat (limited to 'src/backend/utils/cache/syscache.c')
0 files changed, 0 insertions, 0 deletions