sharpetronics/PostgreSQL
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-05-28 00:03:23 -04:00
Code Issues Projects Releases Wiki Activity

Allow incremental sorts for windowing functions

Browse Source 
This expands on the work done in d2d8a229b and allows incremental sort
to be considered during create_window_paths().

Author: David Rowley
Reviewed-by: Daniel Gustafsson, Tomas Vondra
Discussion: https://postgr.es/m/CAApHDvoOHobiA2x13NtWnWLcTXYj9ddpCkv9PnAJQBMegYf_xw%40mail.gmail.com
This commit is contained in:
David Rowley 2020-09-15 23:44:45 +12:00
parent fe4f36bcde
commit 62e221e1c0
3 changed files with 100 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
src/backend/optimizer/plan/planner.c
View File

@ -4582,14 +4582,17 @@ create_window_paths(PlannerInfo *root,
/*
* Consider computing window functions starting from the existing
* cheapest-total path (which will likely require a sort) as well as any
* existing paths that satisfy root->window_pathkeys (which won't).
* existing paths that satisfy or partially satisfy root->window_pathkeys.
*/
foreach(lc, input_rel->pathlist)
{
Path *path = (Path *) lfirst(lc);
int presorted_keys;
if (path == input_rel->cheapest_total_path ||
pathkeys_contained_in(root->window_pathkeys, path->pathkeys))
pathkeys_count_contained_in(root->window_pathkeys, path->pathkeys,
&presorted_keys) ||
presorted_keys > 0)
create_one_window_path(root,
window_rel,
path,
@ -4664,18 +4667,42 @@ create_one_window_path(PlannerInfo *root,
{
WindowClause *wc = lfirst_node(WindowClause, l);
List *window_pathkeys;
int presorted_keys;
bool is_sorted;
window_pathkeys = make_pathkeys_for_window(root,
wc,
root->processed_tlist);
is_sorted = pathkeys_count_contained_in(window_pathkeys,
path->pathkeys,
&presorted_keys);
/* Sort if necessary */
if (!pathkeys_contained_in(window_pathkeys, path->pathkeys))
if (!is_sorted)
{
path = (Path *) create_sort_path(root, window_rel,
path,
window_pathkeys,
-1.0);
/*
* No presorted keys or incremental sort disabled, just perform a
* complete sort.
*/
if (presorted_keys == 0 || !enable_incremental_sort)
path = (Path *) create_sort_path(root, window_rel,
path,
window_pathkeys,
-1.0);
else
{
/*
* Since we have presorted keys and incremental sort is
* enabled, just use incremental sort.
*/
path = (Path *) create_incremental_sort_path(root,
window_rel,
path,
window_pathkeys,
presorted_keys,
-1.0);
}
}
if (lnext(activeWindows, l))

44
src/test/regress/expected/window.out
View File

@ -3200,6 +3200,50 @@ FROM empsalary;
-> Seq Scan on empsalary
(5 rows)
-- Test incremental sorting
EXPLAIN (COSTS OFF)
SELECT * FROM
(SELECT depname,
empno,
salary,
enroll_date,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date) AS first_emp,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date DESC) AS last_emp
FROM empsalary) emp
WHERE first_emp = 1 OR last_emp = 1;
QUERY PLAN
-----------------------------------------------------------------------------------
Subquery Scan on emp
Filter: ((emp.first_emp = 1) OR (emp.last_emp = 1))
-> WindowAgg
-> Incremental Sort
Sort Key: empsalary.depname, empsalary.enroll_date
Presorted Key: empsalary.depname
-> WindowAgg
-> Sort
Sort Key: empsalary.depname, empsalary.enroll_date DESC
-> Seq Scan on empsalary
(10 rows)
SELECT * FROM
(SELECT depname,
empno,
salary,
enroll_date,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date) AS first_emp,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date DESC) AS last_emp
FROM empsalary) emp
WHERE first_emp = 1 OR last_emp = 1;
depname | empno | salary | enroll_date | first_emp | last_emp
-----------+-------+--------+-------------+-----------+----------
develop | 8 | 6000 | 10-01-2006 | 1 | 5
develop | 7 | 4200 | 01-01-2008 | 5 | 1
personnel | 2 | 3900 | 12-23-2006 | 1 | 2
personnel | 5 | 3500 | 12-10-2007 | 2 | 1
sales | 1 | 5000 | 10-01-2006 | 1 | 3
sales | 4 | 4800 | 08-08-2007 | 3 | 1
(6 rows)
-- cleanup
DROP TABLE empsalary;
-- test user-defined window function with named args and default args

22
src/test/regress/sql/window.sql
View File

@ -936,6 +936,28 @@ SELECT
lag(1) OVER (PARTITION BY depname ORDER BY salary,enroll_date,empno)
FROM empsalary;
-- Test incremental sorting
EXPLAIN (COSTS OFF)
SELECT * FROM
(SELECT depname,
empno,
salary,
enroll_date,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date) AS first_emp,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date DESC) AS last_emp
FROM empsalary) emp
WHERE first_emp = 1 OR last_emp = 1;
SELECT * FROM
(SELECT depname,
empno,
salary,
enroll_date,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date) AS first_emp,
row_number() OVER (PARTITION BY depname ORDER BY enroll_date DESC) AS last_emp
FROM empsalary) emp
WHERE first_emp = 1 OR last_emp = 1;
-- cleanup
DROP TABLE empsalary;