From 456fa635a909ee36f73ca84d340521bd730f265f Mon Sep 17 00:00:00 2001 From: David Rowley Date: Fri, 27 Jan 2023 16:08:41 +1300 Subject: [PATCH] Teach planner about more monotonic window functions 9d9c02ccd introduced runConditions for window functions to allow monotonic window function evaluation to be made more efficient when the window function value went beyond some value that it would never go back from due to its monotonic nature. That commit added prosupport functions to inform the planner that row_number(), rank(), dense_rank() and some forms of count(*) were monotonic. Here we add support for ntile(), cume_dist() and percent_rank(). Reviewed-by: Melanie Plageman Discussion: https://postgr.es/m/CAApHDvqR+VqB8s+xR-24bzJbU8xyFrBszJ17qKgECf7cWxLCaA@mail.gmail.com --- src/backend/utils/adt/windowfuncs.c | 30 ++++++++++++++++++++++++++++ src/test/regress/expected/window.out | 26 +++++++++++++----------- src/test/regress/sql/window.sql | 10 ++++++---- 3 files changed, 50 insertions(+), 16 deletions(-) diff --git a/src/backend/utils/adt/windowfuncs.c b/src/backend/utils/adt/windowfuncs.c index af13b8e53d..b87a624fb2 100644 --- a/src/backend/utils/adt/windowfuncs.c +++ b/src/backend/utils/adt/windowfuncs.c @@ -288,6 +288,15 @@ window_percent_rank_support(PG_FUNCTION_ARGS) { Node *rawreq = (Node *) PG_GETARG_POINTER(0); + if (IsA(rawreq, SupportRequestWFuncMonotonic)) + { + SupportRequestWFuncMonotonic *req = (SupportRequestWFuncMonotonic *) rawreq; + + /* percent_rank() is monotonically increasing */ + req->monotonic = MONOTONICFUNC_INCREASING; + PG_RETURN_POINTER(req); + } + if (IsA(rawreq, SupportRequestOptimizeWindowClause)) { SupportRequestOptimizeWindowClause *req = (SupportRequestOptimizeWindowClause *) rawreq; @@ -362,6 +371,15 @@ window_cume_dist_support(PG_FUNCTION_ARGS) { Node *rawreq = (Node *) PG_GETARG_POINTER(0); + if (IsA(rawreq, SupportRequestWFuncMonotonic)) + { + SupportRequestWFuncMonotonic *req = (SupportRequestWFuncMonotonic *) rawreq; + + /* cume_dist() is monotonically increasing */ + req->monotonic = MONOTONICFUNC_INCREASING; + PG_RETURN_POINTER(req); + } + if (IsA(rawreq, SupportRequestOptimizeWindowClause)) { SupportRequestOptimizeWindowClause *req = (SupportRequestOptimizeWindowClause *) rawreq; @@ -465,6 +483,18 @@ window_ntile_support(PG_FUNCTION_ARGS) { Node *rawreq = (Node *) PG_GETARG_POINTER(0); + if (IsA(rawreq, SupportRequestWFuncMonotonic)) + { + SupportRequestWFuncMonotonic *req = (SupportRequestWFuncMonotonic *) rawreq; + + /* + * ntile() is monotonically increasing as the number of buckets cannot + * change after the first call + */ + req->monotonic = MONOTONICFUNC_INCREASING; + PG_RETURN_POINTER(req); + } + if (IsA(rawreq, SupportRequestOptimizeWindowClause)) { SupportRequestOptimizeWindowClause *req = (SupportRequestOptimizeWindowClause *) rawreq; diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out index 26e2df6da5..747608e3c1 100644 --- a/src/test/regress/expected/window.out +++ b/src/test/regress/expected/window.out @@ -3766,19 +3766,20 @@ SELECT * FROM count(salary) OVER (PARTITION BY depname || '') c1, -- w1 row_number() OVER (PARTITION BY depname) rn, -- w2 count(*) OVER (PARTITION BY depname) c2, -- w2 - count(*) OVER (PARTITION BY '' || depname) c3 -- w3 + count(*) OVER (PARTITION BY '' || depname) c3, -- w3 + ntile(2) OVER (PARTITION BY depname) nt -- w2 FROM empsalary -) e WHERE rn <= 1 AND c1 <= 3; - QUERY PLAN -------------------------------------------------------------------------------------------- +) e WHERE rn <= 1 AND c1 <= 3 AND nt < 2; + QUERY PLAN +----------------------------------------------------------------------------------------------- Subquery Scan on e -> WindowAgg - Filter: ((row_number() OVER (?)) <= 1) + Filter: (((row_number() OVER (?)) <= 1) AND ((ntile(2) OVER (?)) < 2)) Run Condition: (count(empsalary.salary) OVER (?) <= 3) -> Sort Sort Key: (((empsalary.depname)::text || ''::text)) -> WindowAgg - Run Condition: (row_number() OVER (?) <= 1) + Run Condition: ((row_number() OVER (?) <= 1) AND (ntile(2) OVER (?) < 2)) -> Sort Sort Key: empsalary.depname -> WindowAgg @@ -3793,13 +3794,14 @@ SELECT * FROM count(salary) OVER (PARTITION BY depname || '') c1, -- w1 row_number() OVER (PARTITION BY depname) rn, -- w2 count(*) OVER (PARTITION BY depname) c2, -- w2 - count(*) OVER (PARTITION BY '' || depname) c3 -- w3 + count(*) OVER (PARTITION BY '' || depname) c3, -- w3 + ntile(2) OVER (PARTITION BY depname) nt -- w2 FROM empsalary -) e WHERE rn <= 1 AND c1 <= 3; - depname | empno | salary | enroll_date | c1 | rn | c2 | c3 ------------+-------+--------+-------------+----+----+----+---- - personnel | 5 | 3500 | 12-10-2007 | 2 | 1 | 2 | 2 - sales | 3 | 4800 | 08-01-2007 | 3 | 1 | 3 | 3 +) e WHERE rn <= 1 AND c1 <= 3 AND nt < 2; + depname | empno | salary | enroll_date | c1 | rn | c2 | c3 | nt +-----------+-------+--------+-------------+----+----+----+----+---- + personnel | 5 | 3500 | 12-10-2007 | 2 | 1 | 2 | 2 | 1 + sales | 3 | 4800 | 08-01-2007 | 3 | 1 | 3 | 3 | 1 (2 rows) -- Tests to ensure we don't push down the run condition when it's not valid to diff --git a/src/test/regress/sql/window.sql b/src/test/regress/sql/window.sql index b7bd0a83da..1009b438de 100644 --- a/src/test/regress/sql/window.sql +++ b/src/test/regress/sql/window.sql @@ -1220,9 +1220,10 @@ SELECT * FROM count(salary) OVER (PARTITION BY depname || '') c1, -- w1 row_number() OVER (PARTITION BY depname) rn, -- w2 count(*) OVER (PARTITION BY depname) c2, -- w2 - count(*) OVER (PARTITION BY '' || depname) c3 -- w3 + count(*) OVER (PARTITION BY '' || depname) c3, -- w3 + ntile(2) OVER (PARTITION BY depname) nt -- w2 FROM empsalary -) e WHERE rn <= 1 AND c1 <= 3; +) e WHERE rn <= 1 AND c1 <= 3 AND nt < 2; -- Ensure we correctly filter out all of the run conditions from each window SELECT * FROM @@ -1230,9 +1231,10 @@ SELECT * FROM count(salary) OVER (PARTITION BY depname || '') c1, -- w1 row_number() OVER (PARTITION BY depname) rn, -- w2 count(*) OVER (PARTITION BY depname) c2, -- w2 - count(*) OVER (PARTITION BY '' || depname) c3 -- w3 + count(*) OVER (PARTITION BY '' || depname) c3, -- w3 + ntile(2) OVER (PARTITION BY depname) nt -- w2 FROM empsalary -) e WHERE rn <= 1 AND c1 <= 3; +) e WHERE rn <= 1 AND c1 <= 3 AND nt < 2; -- Tests to ensure we don't push down the run condition when it's not valid to -- do so. -- 2.30.2