Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit29f114b

Browse files
committed
Allow subquery pullup to wrap a PlaceHolderVar in another one.
The code for wrapping subquery output expressions in PlaceHolderVarsbelieved that if the expression already was a PlaceHolderVar, it wasnever necessary to wrap that in another one. That's wrong if theexpression is underneath an outer join and involves a lateralreference to outside that scope: failing to add an additional PHVrisks evaluating the expression at the wrong place and hence notforcing it to null when the outer join should do so. This is anoversight in commit9e7e29c, which added logic to forcibly wraplateral-reference Vars in PlaceHolderVars, but didn't see that theadjacent case for PlaceHolderVars needed the same treatment.The test case we have for this doesn't fail before4be058f, but nowthat I see the problem I wonder if it is possible to demonstraterelated errors before that. That's moot though, since all suchbranches are out of support.Per bug #18284 from Holger Reise. Back-patch to all supportedbranches.Discussion:https://postgr.es/m/18284-47505a20c23647f8@postgresql.org
1 parenta7097ca commit29f114b

File tree

3 files changed

+46
-2
lines changed

3 files changed

+46
-2
lines changed

‎src/backend/optimizer/prep/prepjointree.c

Lines changed: 7 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2435,8 +2435,13 @@ pullup_replace_vars_callback(Var *var,
24352435
elseif (newnode&&IsA(newnode,PlaceHolderVar)&&
24362436
((PlaceHolderVar*)newnode)->phlevelsup==0)
24372437
{
2438-
/* No need to wrap a PlaceHolderVar with another one, either */
2439-
wrap= false;
2438+
/* The same rules apply for a PlaceHolderVar */
2439+
if (rcon->target_rte->lateral&&
2440+
!bms_is_subset(((PlaceHolderVar*)newnode)->phrels,
2441+
rcon->relids))
2442+
wrap= true;
2443+
else
2444+
wrap= false;
24402445
}
24412446
else
24422447
{

‎src/test/regress/expected/join.out

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -7980,6 +7980,33 @@ select * from
79807980
Output: (COALESCE((COALESCE(b.q2, '42'::bigint)), d.q2))
79817981
(24 rows)
79827982

7983+
-- another case requiring nested PlaceHolderVars
7984+
explain (verbose, costs off)
7985+
select * from
7986+
(select 0 as val0) as ss0
7987+
left join (select 1 as val) as ss1 on true
7988+
left join lateral (select ss1.val as val_filtered where false) as ss2 on true;
7989+
QUERY PLAN
7990+
--------------------------------
7991+
Nested Loop Left Join
7992+
Output: 0, (1), ((1))
7993+
Join Filter: false
7994+
-> Result
7995+
Output: 1
7996+
-> Result
7997+
Output: (1)
7998+
One-Time Filter: false
7999+
(8 rows)
8000+
8001+
select * from
8002+
(select 0 as val0) as ss0
8003+
left join (select 1 as val) as ss1 on true
8004+
left join lateral (select ss1.val as val_filtered where false) as ss2 on true;
8005+
val0 | val | val_filtered
8006+
------+-----+--------------
8007+
0 | 1 |
8008+
(1 row)
8009+
79838010
-- case that breaks the old ph_may_need optimization
79848011
explain (verbose, costs off)
79858012
select c.*,a.*,ss1.q1,ss2.q1,ss3.* from

‎src/test/regress/sql/join.sql

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2950,6 +2950,18 @@ select * from
29502950
)onc.q2=ss2.q1,
29512951
lateral (selectss2.y offset0) ss3;
29522952

2953+
-- another case requiring nested PlaceHolderVars
2954+
explain (verbose, costs off)
2955+
select*from
2956+
(select0as val0)as ss0
2957+
left join (select1as val)as ss1on true
2958+
left join lateral (selectss1.valas val_filteredwhere false)as ss2on true;
2959+
2960+
select*from
2961+
(select0as val0)as ss0
2962+
left join (select1as val)as ss1on true
2963+
left join lateral (selectss1.valas val_filteredwhere false)as ss2on true;
2964+
29532965
-- case that breaks the old ph_may_need optimization
29542966
explain (verbose, costs off)
29552967
select c.*,a.*,ss1.q1,ss2.q1,ss3.*from

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp