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[CF 5698] v1 - Simplify COALESCE with single argument
This branch was automatically generated by a robot using patches from an email thread registered at: https://commitfest.postgresql.org/patch/5698 The branch will be overwritten each time a new patch version is posted to the thread, and also periodically to check for bitrot caused by changes on the master branch. Patch(es): https://www.postgresql.org/message-id/[email protected] Author(s): Maksim Milyutin
2 parents fd7d7b7 + bb7f0f9 commit 83e4a46

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5 files changed

+55
-48
lines changed

5 files changed

+55
-48
lines changed

‎src/backend/optimizer/util/clauses.c‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3333,6 +3333,13 @@ eval_const_expressions_mutator(Node *node,
33333333
-1,
33343334
coalesceexpr->coalescecollid);
33353335

3336+
/*
3337+
* COALESCE with single valued argument looks like identity
3338+
* function so that it's converged to its single argument
3339+
*/
3340+
if (list_length(newargs) == 1)
3341+
return (Node *) linitial(newargs);
3342+
33363343
newcoalesce = makeNode(CoalesceExpr);
33373344
newcoalesce->coalescetype = coalesceexpr->coalescetype;
33383345
newcoalesce->coalescecollid = coalesceexpr->coalescecollid;

‎src/test/regress/expected/join.out‎

Lines changed: 16 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -5626,14 +5626,14 @@ select * from
56265626
(select 1 as id) as xx
56275627
left join
56285628
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
5629-
on (xx.id = coalesce(yy.id));
5630-
QUERY PLAN
5631-
---------------------------------------
5629+
on (xx.id = coalesce(yy.id, 0));
5630+
QUERY PLAN
5631+
----------------------------------------
56325632
Nested Loop Left Join
56335633
-> Result
56345634
-> Hash Full Join
56355635
Hash Cond: (a1.unique1 = (1))
5636-
Filter: (1 = COALESCE((1)))
5636+
Filter: (1 = COALESCE((1), 0))
56375637
-> Seq Scan on tenk1 a1
56385638
-> Hash
56395639
-> Result
@@ -5643,7 +5643,7 @@ select * from
56435643
(select 1 as id) as xx
56445644
left join
56455645
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
5646-
on (xx.id = coalesce(yy.id));
5646+
on (xx.id = coalesce(yy.id, 0));
56475647
id | unique1 | unique2 | two | four | ten | twenty | hundred | thousand | twothousand | fivethous | tenthous | odd | even | stringu1 | stringu2 | string4 | id
56485648
----+---------+---------+-----+------+-----+--------+---------+----------+-------------+-----------+----------+-----+------+----------+----------+---------+----
56495649
1 | 1 | 2838 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 3 | BAAAAA | EFEAAA | OOOOxx | 1
@@ -8411,20 +8411,20 @@ select * from int4_tbl i left join
84118411

84128412
explain (verbose, costs off)
84138413
select * from int4_tbl i left join
8414-
lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
8415-
QUERY PLAN
8416-
-------------------------------------
8414+
lateral (select coalesce(i, row(0)::int4_tbl) from int2_tbl j where i.f1 = j.f1) k on true;
8415+
QUERY PLAN
8416+
------------------------------------------------------
84178417
Nested Loop Left Join
8418-
Output: i.f1, (COALESCE(i.*))
8418+
Output: i.f1, (COALESCE(i.*, '(0)'::int4_tbl))
84198419
-> Seq Scan on public.int4_tbl i
84208420
Output: i.f1, i.*
84218421
-> Seq Scan on public.int2_tbl j
8422-
Output: j.f1, COALESCE(i.*)
8422+
Output: j.f1, COALESCE(i.*, '(0)'::int4_tbl)
84238423
Filter: (i.f1 = j.f1)
84248424
(7 rows)
84258425

84268426
select * from int4_tbl i left join
8427-
lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
8427+
lateral (select coalesce(i, row(0)::int4_tbl) from int2_tbl j where i.f1 = j.f1) k on true;
84288428
f1 | coalesce
84298429
-------------+----------
84308430
0 | (0)
@@ -9593,14 +9593,14 @@ CREATE STATISTICS group_tbl_stat (ndistinct) ON a, b FROM group_tbl;
95939593
ANALYZE group_tbl;
95949594
EXPLAIN (COSTS OFF)
95959595
SELECT 1 FROM group_tbl t1
9596-
LEFT JOIN (SELECT a c1, COALESCE(a) c2 FROM group_tbl t2) s ON TRUE
9596+
LEFT JOIN (SELECT a c1, COALESCE(a, 0) c2 FROM group_tbl t2) s ON TRUE
95979597
GROUP BY s.c1, s.c2;
9598-
QUERY PLAN
9599-
--------------------------------------------
9598+
QUERY PLAN
9599+
---------------------------------------------
96009600
Group
9601-
Group Key: t2.a, (COALESCE(t2.a))
9601+
Group Key: t2.a, (COALESCE(t2.a, 0))
96029602
-> Sort
9603-
Sort Key: t2.a, (COALESCE(t2.a))
9603+
Sort Key: t2.a, (COALESCE(t2.a, 0))
96049604
-> Nested Loop Left Join
96059605
-> Seq Scan on group_tbl t1
96069606
-> Seq Scan on group_tbl t2

‎src/test/regress/expected/subselect.out‎

Lines changed: 23 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -2127,30 +2127,30 @@ explain (verbose, costs off)
21272127
select ss2.* from
21282128
int8_tbl t1 left join
21292129
(int8_tbl t2 left join
2130-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
2130+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
21312131
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
21322132
on t1.q2 = ss2.q1
21332133
order by 1, 2, 3;
2134-
QUERY PLAN
2135-
----------------------------------------------------------------
2134+
QUERY PLAN
2135+
-----------------------------------------------------------------------------
21362136
Sort
2137-
Output: (COALESCE(t3.q1)), t4.q1, t4.q2
2138-
Sort Key: (COALESCE(t3.q1)), t4.q1, t4.q2
2137+
Output: (COALESCE(t3.q1, '0'::bigint)), t4.q1, t4.q2
2138+
Sort Key: (COALESCE(t3.q1, '0'::bigint)), t4.q1, t4.q2
21392139
-> Hash Right Join
2140-
Output: (COALESCE(t3.q1)), t4.q1, t4.q2
2140+
Output: (COALESCE(t3.q1, '0'::bigint)), t4.q1, t4.q2
21412141
Hash Cond: (t4.q1 = t1.q2)
21422142
-> Hash Join
2143-
Output: (COALESCE(t3.q1)), t4.q1, t4.q2
2143+
Output: (COALESCE(t3.q1, '0'::bigint)), t4.q1, t4.q2
21442144
Hash Cond: (t2.q2 = t4.q1)
21452145
-> Hash Left Join
2146-
Output: t2.q2, (COALESCE(t3.q1))
2146+
Output: t2.q2, (COALESCE(t3.q1, '0'::bigint))
21472147
Hash Cond: (t2.q1 = t3.q2)
21482148
-> Seq Scan on public.int8_tbl t2
21492149
Output: t2.q1, t2.q2
21502150
-> Hash
2151-
Output: t3.q2, (COALESCE(t3.q1))
2151+
Output: t3.q2, (COALESCE(t3.q1, '0'::bigint))
21522152
-> Seq Scan on public.int8_tbl t3
2153-
Output: t3.q2, COALESCE(t3.q1)
2153+
Output: t3.q2, COALESCE(t3.q1, '0'::bigint)
21542154
-> Hash
21552155
Output: t4.q1, t4.q2
21562156
-> Seq Scan on public.int8_tbl t4
@@ -2164,7 +2164,7 @@ order by 1, 2, 3;
21642164
select ss2.* from
21652165
int8_tbl t1 left join
21662166
(int8_tbl t2 left join
2167-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
2167+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
21682168
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
21692169
on t1.q2 = ss2.q1
21702170
order by 1, 2, 3;
@@ -2201,32 +2201,32 @@ explain (verbose, costs off)
22012201
select ss2.* from
22022202
int8_tbl t1 left join
22032203
(int8_tbl t2 left join
2204-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
2204+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
22052205
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
22062206
on t1.q2 = ss2.q1
22072207
order by 1, 2, 3;
2208-
QUERY PLAN
2209-
----------------------------------------------------------------
2208+
QUERY PLAN
2209+
-----------------------------------------------------------------------------
22102210
Sort
2211-
Output: ((COALESCE(t3.q1))), t4.q1, t4.q2
2212-
Sort Key: ((COALESCE(t3.q1))), t4.q1, t4.q2
2211+
Output: ((COALESCE(t3.q1, '0'::bigint))), t4.q1, t4.q2
2212+
Sort Key: ((COALESCE(t3.q1, '0'::bigint))), t4.q1, t4.q2
22132213
-> Hash Right Join
2214-
Output: ((COALESCE(t3.q1))), t4.q1, t4.q2
2214+
Output: ((COALESCE(t3.q1, '0'::bigint))), t4.q1, t4.q2
22152215
Hash Cond: (t4.q1 = t1.q2)
22162216
-> Nested Loop
2217-
Output: t4.q1, t4.q2, ((COALESCE(t3.q1)))
2217+
Output: t4.q1, t4.q2, ((COALESCE(t3.q1, '0'::bigint)))
22182218
Join Filter: (t2.q2 = t4.q1)
22192219
-> Hash Left Join
2220-
Output: t2.q2, (COALESCE(t3.q1))
2220+
Output: t2.q2, (COALESCE(t3.q1, '0'::bigint))
22212221
Hash Cond: (t2.q1 = t3.q2)
22222222
-> Seq Scan on public.int8_tbl t2
22232223
Output: t2.q1, t2.q2
22242224
-> Hash
2225-
Output: t3.q2, (COALESCE(t3.q1))
2225+
Output: t3.q2, (COALESCE(t3.q1, '0'::bigint))
22262226
-> Seq Scan on public.int8_tbl t3
2227-
Output: t3.q2, COALESCE(t3.q1)
2227+
Output: t3.q2, COALESCE(t3.q1, '0'::bigint)
22282228
-> Seq Scan on public.int8_tbl t4
2229-
Output: t4.q1, t4.q2, (COALESCE(t3.q1))
2229+
Output: t4.q1, t4.q2, (COALESCE(t3.q1, '0'::bigint))
22302230
-> Hash
22312231
Output: t1.q2
22322232
-> Seq Scan on public.int8_tbl t1
@@ -2236,7 +2236,7 @@ order by 1, 2, 3;
22362236
select ss2.* from
22372237
int8_tbl t1 left join
22382238
(int8_tbl t2 left join
2239-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
2239+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
22402240
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
22412241
on t1.q2 = ss2.q1
22422242
order by 1, 2, 3;

‎src/test/regress/sql/join.sql‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1977,13 +1977,13 @@ select * from
19771977
(select 1 as id) as xx
19781978
left join
19791979
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
1980-
on (xx.id = coalesce(yy.id));
1980+
on (xx.id = coalesce(yy.id, 0));
19811981

19821982
select * from
19831983
(select 1 as id) as xx
19841984
left join
19851985
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
1986-
on (xx.id = coalesce(yy.id));
1986+
on (xx.id = coalesce(yy.id, 0));
19871987

19881988
--
19891989
-- test ability to push constants through outer join clauses
@@ -3169,9 +3169,9 @@ select * from int4_tbl i left join
31693169
lateral (select * from int2_tbl j where i.f1 = j.f1) k on true;
31703170
explain (verbose, costs off)
31713171
select * from int4_tbl i left join
3172-
lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
3172+
lateral (select coalesce(i, row(0)::int4_tbl) from int2_tbl j where i.f1 = j.f1) k on true;
31733173
select * from int4_tbl i left join
3174-
lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
3174+
lateral (select coalesce(i, row(0)::int4_tbl) from int2_tbl j where i.f1 = j.f1) k on true;
31753175
explain (verbose, costs off)
31763176
select * from int4_tbl a,
31773177
lateral (
@@ -3637,7 +3637,7 @@ ANALYZE group_tbl;
36373637

36383638
EXPLAIN (COSTS OFF)
36393639
SELECT 1 FROM group_tbl t1
3640-
LEFT JOIN (SELECT a c1, COALESCE(a) c2 FROM group_tbl t2) s ON TRUE
3640+
LEFT JOIN (SELECT a c1, COALESCE(a, 0) c2 FROM group_tbl t2) s ON TRUE
36413641
GROUP BY s.c1, s.c2;
36423642

36433643
DROP TABLE group_tbl;

‎src/test/regress/sql/subselect.sql‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1041,15 +1041,15 @@ explain (verbose, costs off)
10411041
select ss2.* from
10421042
int8_tbl t1 left join
10431043
(int8_tbl t2 left join
1044-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
1044+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
10451045
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
10461046
on t1.q2 = ss2.q1
10471047
order by 1, 2, 3;
10481048

10491049
select ss2.* from
10501050
int8_tbl t1 left join
10511051
(int8_tbl t2 left join
1052-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
1052+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
10531053
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
10541054
on t1.q2 = ss2.q1
10551055
order by 1, 2, 3;
@@ -1059,15 +1059,15 @@ explain (verbose, costs off)
10591059
select ss2.* from
10601060
int8_tbl t1 left join
10611061
(int8_tbl t2 left join
1062-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
1062+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
10631063
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
10641064
on t1.q2 = ss2.q1
10651065
order by 1, 2, 3;
10661066

10671067
select ss2.* from
10681068
int8_tbl t1 left join
10691069
(int8_tbl t2 left join
1070-
(select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
1070+
(select coalesce(q1, 0) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
10711071
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
10721072
on t1.q2 = ss2.q1
10731073
order by 1, 2, 3;

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