diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-03-24 11:47:41 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-03-24 11:47:41 -0400 |
| commit | 0bd7af082ace135581bb13a6bd2d88e68c66a3e0 (patch) | |
| tree | 412ad873ef762b761baaab0577cb4d36b6c0a240 /src/backend/utils/misc/guc.c | |
| parent | a47651447f01562dac2e007db03733e750d45b6b (diff) | |
Invent recursive_worktable_factor GUC to replace hard-wired constant.
Up to now, the planner estimated the size of a recursive query's
worktable as 10 times the size of the non-recursive term. It's hard
to see how to do significantly better than that automatically, but
we can give users control over the multiplier to allow tuning for
specific use-cases. The default behavior remains the same.
Simon Riggs
Discussion: https://postgr.es/m/CANbhV-EuaLm4H3g0+BSTYHEGxJj3Kht0R+rJ8vT57Dejnh=_nA@mail.gmail.com
Diffstat (limited to 'src/backend/utils/misc/guc.c')
| -rw-r--r-- | src/backend/utils/misc/guc.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index f70f7f5c01e..b86137dc385 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -3741,6 +3741,18 @@ static struct config_real ConfigureNamesReal[] = }, { + {"recursive_worktable_factor", PGC_USERSET, QUERY_TUNING_OTHER, + gettext_noop("Sets the planner's estimate of the average size " + "of a recursive query's working table."), + NULL, + GUC_EXPLAIN + }, + &recursive_worktable_factor, + DEFAULT_RECURSIVE_WORKTABLE_FACTOR, 0.001, 1000000.0, + NULL, NULL, NULL + }, + + { {"geqo_selection_bias", PGC_USERSET, QUERY_TUNING_GEQO, gettext_noop("GEQO: selective pressure within the population."), NULL, |