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-rw-r--r--src/backend/optimizer/util/clauses.c7
-rw-r--r--src/test/regress/expected/join.out32
-rw-r--r--src/test/regress/expected/subselect.out46
-rw-r--r--src/test/regress/sql/join.sql10
-rw-r--r--src/test/regress/sql/subselect.sql8
5 files changed, 55 insertions, 48 deletions
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 26a3e050086..f45131c34c5 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -3333,6 +3333,13 @@ eval_const_expressions_mutator(Node *node,
-1,
coalesceexpr->coalescecollid);
+ /*
+ * If there's exactly one surviving argument, we no longer
+ * need COALESCE at all: the result is that argument
+ */
+ if (list_length(newargs) == 1)
+ return (Node *) linitial(newargs);
+
newcoalesce = makeNode(CoalesceExpr);
newcoalesce->coalescetype = coalesceexpr->coalescetype;
newcoalesce->coalescecollid = coalesceexpr->coalescecollid;
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 390aabfb34b..46ddfa844c5 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -5626,14 +5626,14 @@ select * from
(select 1 as id) as xx
left join
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
- on (xx.id = coalesce(yy.id));
- QUERY PLAN
----------------------------------------
+ on (xx.id = coalesce(yy.id, yy.id));
+ QUERY PLAN
+------------------------------------------
Nested Loop Left Join
-> Result
-> Hash Full Join
Hash Cond: (a1.unique1 = (1))
- Filter: (1 = COALESCE((1)))
+ Filter: (1 = COALESCE((1), (1)))
-> Seq Scan on tenk1 a1
-> Hash
-> Result
@@ -5643,7 +5643,7 @@ select * from
(select 1 as id) as xx
left join
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
- on (xx.id = coalesce(yy.id));
+ on (xx.id = coalesce(yy.id, yy.id));
id | unique1 | unique2 | two | four | ten | twenty | hundred | thousand | twothousand | fivethous | tenthous | odd | even | stringu1 | stringu2 | string4 | id
----+---------+---------+-----+------+-----+--------+---------+----------+-------------+-----------+----------+-----+------+----------+----------+---------+----
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
explain (verbose, costs off)
select * from int4_tbl i left join
- lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
- QUERY PLAN
--------------------------------------
+ lateral (select coalesce(i, i) from int2_tbl j where i.f1 = j.f1) k on true;
+ QUERY PLAN
+------------------------------------------
Nested Loop Left Join
- Output: i.f1, (COALESCE(i.*))
+ Output: i.f1, (COALESCE(i.*, i.*))
-> Seq Scan on public.int4_tbl i
Output: i.f1, i.*
-> Seq Scan on public.int2_tbl j
- Output: j.f1, COALESCE(i.*)
+ Output: j.f1, COALESCE(i.*, i.*)
Filter: (i.f1 = j.f1)
(7 rows)
select * from int4_tbl i left join
- lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
+ lateral (select coalesce(i, i) from int2_tbl j where i.f1 = j.f1) k on true;
f1 | coalesce
-------------+----------
0 | (0)
@@ -9593,14 +9593,14 @@ CREATE STATISTICS group_tbl_stat (ndistinct) ON a, b FROM group_tbl;
ANALYZE group_tbl;
EXPLAIN (COSTS OFF)
SELECT 1 FROM group_tbl t1
- LEFT JOIN (SELECT a c1, COALESCE(a) c2 FROM group_tbl t2) s ON TRUE
+ LEFT JOIN (SELECT a c1, COALESCE(a, a) c2 FROM group_tbl t2) s ON TRUE
GROUP BY s.c1, s.c2;
- QUERY PLAN
---------------------------------------------
+ QUERY PLAN
+------------------------------------------------
Group
- Group Key: t2.a, (COALESCE(t2.a))
+ Group Key: t2.a, (COALESCE(t2.a, t2.a))
-> Sort
- Sort Key: t2.a, (COALESCE(t2.a))
+ Sort Key: t2.a, (COALESCE(t2.a, t2.a))
-> Nested Loop Left Join
-> Seq Scan on group_tbl t1
-> Seq Scan on group_tbl t2
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index 40d8056fcea..18fed63e738 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -2127,30 +2127,30 @@ explain (verbose, costs off)
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
- QUERY PLAN
-----------------------------------------------------------------
+ QUERY PLAN
+-----------------------------------------------------------------------
Sort
- Output: (COALESCE(t3.q1)), t4.q1, t4.q2
- Sort Key: (COALESCE(t3.q1)), t4.q1, t4.q2
+ Output: (COALESCE(t3.q1, t3.q1)), t4.q1, t4.q2
+ Sort Key: (COALESCE(t3.q1, t3.q1)), t4.q1, t4.q2
-> Hash Right Join
- Output: (COALESCE(t3.q1)), t4.q1, t4.q2
+ Output: (COALESCE(t3.q1, t3.q1)), t4.q1, t4.q2
Hash Cond: (t4.q1 = t1.q2)
-> Hash Join
- Output: (COALESCE(t3.q1)), t4.q1, t4.q2
+ Output: (COALESCE(t3.q1, t3.q1)), t4.q1, t4.q2
Hash Cond: (t2.q2 = t4.q1)
-> Hash Left Join
- Output: t2.q2, (COALESCE(t3.q1))
+ Output: t2.q2, (COALESCE(t3.q1, t3.q1))
Hash Cond: (t2.q1 = t3.q2)
-> Seq Scan on public.int8_tbl t2
Output: t2.q1, t2.q2
-> Hash
- Output: t3.q2, (COALESCE(t3.q1))
+ Output: t3.q2, (COALESCE(t3.q1, t3.q1))
-> Seq Scan on public.int8_tbl t3
- Output: t3.q2, COALESCE(t3.q1)
+ Output: t3.q2, COALESCE(t3.q1, t3.q1)
-> Hash
Output: t4.q1, t4.q2
-> Seq Scan on public.int8_tbl t4
@@ -2164,7 +2164,7 @@ order by 1, 2, 3;
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
@@ -2201,32 +2201,32 @@ explain (verbose, costs off)
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
- QUERY PLAN
-----------------------------------------------------------------
+ QUERY PLAN
+-----------------------------------------------------------------------
Sort
- Output: ((COALESCE(t3.q1))), t4.q1, t4.q2
- Sort Key: ((COALESCE(t3.q1))), t4.q1, t4.q2
+ Output: ((COALESCE(t3.q1, t3.q1))), t4.q1, t4.q2
+ Sort Key: ((COALESCE(t3.q1, t3.q1))), t4.q1, t4.q2
-> Hash Right Join
- Output: ((COALESCE(t3.q1))), t4.q1, t4.q2
+ Output: ((COALESCE(t3.q1, t3.q1))), t4.q1, t4.q2
Hash Cond: (t4.q1 = t1.q2)
-> Nested Loop
- Output: t4.q1, t4.q2, ((COALESCE(t3.q1)))
+ Output: t4.q1, t4.q2, ((COALESCE(t3.q1, t3.q1)))
Join Filter: (t2.q2 = t4.q1)
-> Hash Left Join
- Output: t2.q2, (COALESCE(t3.q1))
+ Output: t2.q2, (COALESCE(t3.q1, t3.q1))
Hash Cond: (t2.q1 = t3.q2)
-> Seq Scan on public.int8_tbl t2
Output: t2.q1, t2.q2
-> Hash
- Output: t3.q2, (COALESCE(t3.q1))
+ Output: t3.q2, (COALESCE(t3.q1, t3.q1))
-> Seq Scan on public.int8_tbl t3
- Output: t3.q2, COALESCE(t3.q1)
+ Output: t3.q2, COALESCE(t3.q1, t3.q1)
-> Seq Scan on public.int8_tbl t4
- Output: t4.q1, t4.q2, (COALESCE(t3.q1))
+ Output: t4.q1, t4.q2, (COALESCE(t3.q1, t3.q1))
-> Hash
Output: t1.q2
-> Seq Scan on public.int8_tbl t1
@@ -2236,7 +2236,7 @@ order by 1, 2, 3;
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index f6e7070db65..5f0a475894d 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1977,13 +1977,13 @@ select * from
(select 1 as id) as xx
left join
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
- on (xx.id = coalesce(yy.id));
+ on (xx.id = coalesce(yy.id, yy.id));
select * from
(select 1 as id) as xx
left join
(tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
- on (xx.id = coalesce(yy.id));
+ on (xx.id = coalesce(yy.id, yy.id));
--
-- test ability to push constants through outer join clauses
@@ -3169,9 +3169,9 @@ select * from int4_tbl i left join
lateral (select * from int2_tbl j where i.f1 = j.f1) k on true;
explain (verbose, costs off)
select * from int4_tbl i left join
- lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
+ lateral (select coalesce(i, i) from int2_tbl j where i.f1 = j.f1) k on true;
select * from int4_tbl i left join
- lateral (select coalesce(i) from int2_tbl j where i.f1 = j.f1) k on true;
+ lateral (select coalesce(i, i) from int2_tbl j where i.f1 = j.f1) k on true;
explain (verbose, costs off)
select * from int4_tbl a,
lateral (
@@ -3637,7 +3637,7 @@ ANALYZE group_tbl;
EXPLAIN (COSTS OFF)
SELECT 1 FROM group_tbl t1
- LEFT JOIN (SELECT a c1, COALESCE(a) c2 FROM group_tbl t2) s ON TRUE
+ LEFT JOIN (SELECT a c1, COALESCE(a, a) c2 FROM group_tbl t2) s ON TRUE
GROUP BY s.c1, s.c2;
DROP TABLE group_tbl;
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index fec38ef85a6..d9a841fbc9f 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -1041,7 +1041,7 @@ explain (verbose, costs off)
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
@@ -1049,7 +1049,7 @@ order by 1, 2, 3;
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 inner join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
@@ -1059,7 +1059,7 @@ explain (verbose, costs off)
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
@@ -1067,7 +1067,7 @@ order by 1, 2, 3;
select ss2.* from
int8_tbl t1 left join
(int8_tbl t2 left join
- (select coalesce(q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
+ (select coalesce(q1, q1) as x, * from int8_tbl t3) ss1 on t2.q1 = ss1.q2 left join
lateral (select ss1.x as y, * from int8_tbl t4) ss2 on t2.q2 = ss2.q1)
on t1.q2 = ss2.q1
order by 1, 2, 3;
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-13 09:56:25 +0000