postgres.git / summary / log / commit / refs
commit 456fa635a909ee36f73ca84d340521bd730f265f
Author: David Rowley <drowley@postgresql.org>
Date: Fri Jan 27 03:08:41 2023 +0000
First released in: 16.0
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 af13b8e53d5..b87a624fb2f 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 26e2df6da55..747608e3c14 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 b7bd0a83da4..1009b438def 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.
[parent: 783d8abc3b63]