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| author | Alexander Korotkov <akorotkov@postgresql.org> | 2024-04-08 01:27:28 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2024-04-08 01:27:52 +0300 |
| commit | 72bd38cc99a15da6f97373fae98027c908c398ea (patch) | |
| tree | 090cdaccbab7286e709f6ebe9a4ddc6142e936f8 /src/backend/utils/misc/postgresql.conf.sample | |
| parent | 75a47b6a0dc4a235307e1acd1a6b3845cb881e55 (diff) | |
| download | postgresql-72bd38cc99a15da6f97373fae98027c908c398ea.tar.gz postgresql-72bd38cc99a15da6f97373fae98027c908c398ea.zip | |
Transform OR clauses to ANY expression
Replace (expr op C1) OR (expr op C2) ... with expr op ANY(ARRAY[C1, C2, ...])
on the preliminary stage of optimization when we are still working with the
expression tree.
Here Cn is a n-th constant expression, 'expr' is non-constant expression, 'op'
is an operator which returns boolean result and has a commuter (for the case
of reverse order of constant and non-constant parts of the expression,
like 'Cn op expr').
Sometimes it can lead to not optimal plan. This is why there is a
or_to_any_transform_limit GUC. It specifies a threshold value of length of
arguments in an OR expression that triggers the OR-to-ANY transformation.
Generally, more groupable OR arguments mean that transformation will be more
likely to win than to lose.
Discussion: https://postgr.es/m/567ED6CA.2040504%40sigaev.ru
Author: Alena Rybakina <lena.ribackina@yandex.ru>
Author: Andrey Lepikhov <a.lepikhov@postgrespro.ru>
Reviewed-by: Peter Geoghegan <pg@bowt.ie>
Reviewed-by: Ranier Vilela <ranier.vf@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Jian He <jian.universality@gmail.com>
Diffstat (limited to 'src/backend/utils/misc/postgresql.conf.sample')
| -rw-r--r-- | src/backend/utils/misc/postgresql.conf.sample | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 2166ea4a87a..15b14ba8507 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -392,6 +392,7 @@ # - Planner Method Configuration - #enable_async_append = on +#or_to_any_transform_limit = 0 #enable_bitmapscan = on #enable_gathermerge = on #enable_hashagg = on |