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Subject: BUG #19493: Assertion failure in pg_plan_advice with EXISTS subquery
 and DO_NOT_SCAN advice
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: n.kalinin@postgrespro.ru
Reply-To: n.kalinin@postgrespro.ru, pgsql-bugs@lists.postgresql.org
Date: Tue, 26 May 2026 14:44:38 +0000
Message-ID: <19493-5878eac7a2525c23@postgresql.org>
Auto-Submitted: auto-generated
Archived-At: 
 <https://www.postgresql.org/message-id/19493-5878eac7a2525c23%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19493
Logged by:          Nikita Kalinin
Email address:      n.kalinin@postgrespro.ru
PostgreSQL version: 18.4
Operating system:   Fedora 44
Description:       =20

Hi,
I found an assertion failure in pg_plan_advice.
Reproducer:

LOAD 'pg_plan_advice';

CREATE TABLE a(i int);
CREATE TABLE b(i int);

SET pg_plan_advice.feedback_warnings =3D on;
SET pg_plan_advice.advice =3D 'DO_NOT_SCAN((a))';

EXPLAIN
SELECT *
FROM a
WHERE EXISTS (
    SELECT 1
    FROM b
    WHERE b.i =3D a.i
);

Result:
2026-05-26 21:36:46.452 +07 [83331] LOG:  database system is ready to accept
connections
TRAP: failed Assert("target->ttype =3D=3D PGPA_TARGET_IDENTIFIER"), File:
"pgpa_trove.c", Line: 182, PID: 83390
postgres: nkpit postgres [local] EXPLAIN(ExceptionalCondition+0x57)
[0xa2d077]
/tmp/pg/lib/postgresql/pg_plan_advice.so(+0xb0b2) [0x7fb2c06440b2]
/tmp/pg/lib/postgresql/pg_plan_advice.so(+0x533f) [0x7fb2c063e33f]
postgres: nkpit postgres [local] EXPLAIN(standard_planner+0x1ff) [0x7b51ff]
...
Backtrace:
#0  __pthread_kill_implementation (threadid=3D<optimized out>,
signo=3Dsigno@entry=3D6,
    no_tid=3Dno_tid@entry=3D0) at pthread_kill.c:44
#1  0x00007fb2bf27a8d3 in __pthread_kill_internal (threadid=3D<optimized ou=
t>,
signo=3D6)
    at pthread_kill.c:89
#2  0x00007fb2bf21f48e in __GI_raise (sig=3Dsig@entry=3D6) at
../sysdeps/posix/raise.c:26
#3  0x00007fb2bf2067b3 in __GI_abort () at abort.c:77
#4  0x0000000000a2d098 in ExceptionalCondition (
    conditionName=3DconditionName@entry=3D0x7fb2c0649828 "target->ttype =3D=
=3D
PGPA_TARGET_IDENTIFIER",
    fileName=3DfileName@entry=3D0x7fb2c064a184 "pgpa_trove.c",
lineNumber=3DlineNumber@entry=3D182)
    at assert.c:65
#5  0x00007fb2c06440b2 in pgpa_build_trove (advice_items=3D0x32a59488) at
pgpa_trove.c:182
#6  0x00007fb2c063e33f in pgpa_planner_setup (glob=3D0x32985888,
parse=3D0x32956d60,
    query_string=3D0x329558b0 "EXPLAIN SELECT *\nFROM a\nWHERE EXISTS (SELE=
CT
1 FROM b WHERE b.i =3D a.i);", cursorOptions=3D2048,
tuple_fraction=3D0x7ffe98a152f0, es=3D0x32985308) at pgpa_planner.c:255
#7  0x00000000007b51ff in standard_planner (parse=3D0x32956d60,
query_string=3D<optimized out>,
    cursorOptions=3D2048, boundParams=3D<optimized out>, es=3D0x32985308) at
planner.c:533
#8  0x00000000007b5a0d in planner (parse=3Dparse@entry=3D0x32956d60,
    query_string=3Dquery_string@entry=3D0x329558b0 "EXPLAIN SELECT *\nFROM
a\nWHERE EXISTS (SELECT 1 FROM b WHERE b.i =3D a.i);",
cursorOptions=3DcursorOptions@entry=3D2048,
    boundParams=3DboundParams@entry=3D0x0, es=3Des@entry=3D0x32985308) at
planner.c:342
#9  0x00000000008c297d in pg_plan_query
(querytree=3Dquerytree@entry=3D0x32956d60,
    query_string=3Dquery_string@entry=3D0x329558b0 "EXPLAIN SELECT *\nFROM
a\nWHERE EXISTS (SELECT 1 FROM b WHERE b.i =3D a.i);", cursorOptions=3D2048,
boundParams=3DboundParams@entry=3D0x0,
    es=3Des@entry=3D0x32985308) at postgres.c:917
#10 0x000000000062ed1e in standard_ExplainOneQuery (query=3D0x32956d60,
    cursorOptions=3D<optimized out>, into=3D0x0, es=3D0x32985308,
    queryString=3D0x329558b0 "EXPLAIN SELECT *\nFROM a\nWHERE EXISTS (SELEC=
T 1
FROM b WHERE b.i =3D a.i);", params=3D0x0, queryEnv=3D0x0) at explain.c:359
#11 0x000000000062ef8e in ExplainOneQuery (query=3D<optimized out>,
cursorOptions=3D<optimized out>,
    into=3D<optimized out>, es=3D<optimized out>, pstate=3D<optimized out>,
params=3D<optimized out>)
    at explain.c:315
--Type <RET> for more, q to quit, c to continue without paging--c
#12 0x000000000062f0ae in ExplainQuery (pstate=3D0x32982990, stmt=3D0x32956=
ba0,
params=3D0x0,
    dest=3D0x32985278) at ../../../src/include/nodes/nodes.h:178
#13 0x00000000008c8819 in standard_ProcessUtility (pstmt=3D0x32956c50,
    queryString=3D0x329558b0 "EXPLAIN SELECT *\nFROM a\nWHERE EXISTS (SELEC=
T 1
FROM b WHERE b.i =3D a.i);", readOnlyTree=3D<optimized out>,
context=3DPROCESS_UTILITY_TOPLEVEL, params=3D0x0, queryEnv=3D0x0,
    dest=3D0x32985278, qc=3D0x7ffe98a15660) at utility.c:871
#14 0x00000000008c6b8d in PortalRunUtility (portal=3Dportal@entry=3D0x329f9=
1e0,
pstmt=3D0x32956c50,
    isTopLevel=3DisTopLevel@entry=3Dtrue,
setHoldSnapshot=3DsetHoldSnapshot@entry=3Dtrue,
    dest=3Ddest@entry=3D0x32985278, qc=3Dqc@entry=3D0x7ffe98a15660) at pque=
ry.c:1149
#15 0x00000000008c7060 in FillPortalStore (portal=3Dportal@entry=3D0x329f91=
e0,
    isTopLevel=3DisTopLevel@entry=3Dtrue) at
../../../src/include/nodes/nodes.h:178
#16 0x00000000008c737d in PortalRun (portal=3Dportal@entry=3D0x329f91e0,
    count=3Dcount@entry=3D9223372036854775807, isTopLevel=3DisTopLevel@entr=
y=3Dtrue,
    dest=3Ddest@entry=3D0x32a690d8, altdest=3Daltdest@entry=3D0x32a690d8,
qc=3Dqc@entry=3D0x7ffe98a15830)
    at pquery.c:756
#17 0x00000000008c2f48 in exec_simple_query (
    query_string=3D0x329558b0 "EXPLAIN SELECT *\nFROM a\nWHERE EXISTS (SELE=
CT
1 FROM b WHERE b.i =3D a.i);") at postgres.c:1290
#18 0x00000000008c4a21 in PostgresMain (dbname=3D<optimized out>,
username=3D<optimized out>)
    at postgres.c:4856
#19 0x00000000008bea1d in BackendMain (startup_data=3D<optimized out>,
    startup_data_len=3D<optimized out>) at backend_startup.c:124
#20 0x00000000007fea2e in postmaster_child_launch (child_type=3D<optimized
out>, child_slot=3D1,
    startup_data=3Dstartup_data@entry=3D0x7ffe98a15c80,
startup_data_len=3Dstartup_data_len@entry=3D24,
    client_sock=3Dclient_sock@entry=3D0x7ffe98a15ca0) at launch_backend.c:2=
68
#21 0x0000000000802436 in BackendStartup (client_sock=3D0x7ffe98a15ca0) at
postmaster.c:3627
#22 ServerLoop () at postmaster.c:1728
#23 0x0000000000803ef9 in PostmasterMain (argc=3Dargc@entry=3D3,
argv=3Dargv@entry=3D0x328ff080)
    at postmaster.c:1415
#24 0x00000000004a1a68 in main (argc=3D3, argv=3D0x328ff080) at main.c:231