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Transform OR clauses to ANY expression

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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>
This commit is contained in:
Alexander Korotkov
2024-04-08 01:27:28 +03:00
parent 75a47b6a0d
commit 72bd38cc99
14 changed files with 785 additions and 20 deletions
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12
src/backend/utils/misc/guc_tables.c
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@ -3657,6 +3657,18 @@ struct config_int ConfigureNamesInt[] =
NULL, NULL, NULL
},
{
{"or_to_any_transform_limit", PGC_USERSET, QUERY_TUNING_OTHER,
gettext_noop("Set the minimum length of the list of OR clauses to attempt the OR-to-ANY transformation."),
gettext_noop("Once the limit is reached, the planner will try to replace expression like "
"'x=c1 OR x=c2 ..' to the expression 'x = ANY(ARRAY[c1,c2,..])'"),
GUC_EXPLAIN
},
&or_to_any_transform_limit,
5, -1, INT_MAX,
NULL, NULL, NULL
},
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL