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Subject: BUG #19482: Recursive QueueFKConstraintValidation() lacks stack depth
 check
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: exclusion@gmail.com
Reply-To: exclusion@gmail.com, pgsql-bugs@lists.postgresql.org
Date: Sat, 16 May 2026 11:00:01 +0000
Message-ID: <19482-4cc37cbf52d55235@postgresql.org>
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Archived-At: 
 <https://www.postgresql.org/message-id/19482-4cc37cbf52d55235%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19482
Logged by:          Alexander Lakhin
Email address:      exclusion@gmail.com
PostgreSQL version: 18.4
Operating system:   Ubuntu 24.04
Description:       =20

The following script:
echo "
CREATE TABLE tp0 (a int, PRIMARY KEY (a)) PARTITION BY RANGE(a);
ALTER TABLE tp0 ADD CONSTRAINT fk FOREIGN KEY (a) REFERENCES tp0 NOT VALID;
" | psql

for ((i=3D1;i<=3D48000;i++)); do # may take 2-3 hours
  echo "CREATE TABLE tp$i PARTITION OF tp$(( $i - 1 ))
         FOR VALUES FROM ($i) TO (1000000) PARTITION BY RANGE (a);";
done | psql > psql.log

echo "
ALTER TABLE tp0 VALIDATE CONSTRAINT fk;
" | psql

leads to:
2026-05-16 12:35:43.258 EEST|law|regression|6a083a6f.34aa38|LOG:  statement:
ALTER TABLE tp0 VALIDATE CONSTRAINT fk;
2026-05-16 12:35:56.104 EEST|||6a07f1d1.32a4c7|LOG:  client backend (PID
3451448) was terminated by signal 11: Segmentation fault
2026-05-16 12:35:56.104 EEST|||6a07f1d1.32a4c7|DETAIL:  Failed process was
running: ALTER TABLE tp0 VALIDATE CONSTRAINT fk;

Core was generated by `postgres: law regression 127.0.0.1(48420) ALTER TABLE
'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00005e57e8d06ae9 in hash_initial_lookup (hashp=3D0x5e580f378e10,
hashvalue=3D795799848, bucketptr=3D0x7ffe0c940090) at dynahash.c:1767
1767        bucket =3D calc_bucket(hctl, hashvalue);
(gdb) (gdb) (gdb) (gdb) #0  0x00005e57e8d06ae9 in hash_initial_lookup
(hashp=3D0x5e580f378e10, hashvalue=3D795799848, bucketptr=3D0x7ffe0c940090)=
 at
dynahash.c:1767
#1  0x00005e57e8d0545c in hash_search_with_hash_value (hashp=3D0x5e580f378e=
10,
keyPtr=3D0x7ffe0c94010c, hashvalue=3D795799848, action=3DHASH_FIND, foundPt=
r=3D0x0)
    at dynahash.c:1010
#2  0x00005e57e8d0538a in hash_search (hashp=3D0x5e580f378e10,
keyPtr=3D0x7ffe0c94010c, action=3DHASH_FIND, foundPtr=3D0x0) at dynahash.c:=
961
#3  0x00005e57e8a7c224 in GetPrivateRefCountEntry (buffer=3D125, do_move=3D=
true)
at bufmgr.c:381
#4  0x00005e57e8a8051a in PinBuffer (buf=3D0x762990250980, strategy=3D0x0) =
at
bufmgr.c:3085
...
#20 0x00005e57e8ce0a15 in CheckNNConstraintFetch (relation=3D0x762989504168)
at relcache.c:4619
#21 0x00005e57e8cd9b66 in RelationBuildTupleDesc (relation=3D0x762989504168)
at relcache.c:701
#22 0x00005e57e8cdaa23 in RelationBuildDesc (targetRelId=3D464701,
insertIt=3Dtrue) at relcache.c:1204
#23 0x00005e57e8cdc5cb in RelationIdGetRelation (relationId=3D464701) at
relcache.c:2142
#24 0x00005e57e84d14d2 in relation_open (relationId=3D464701, lockmode=3D4)=
 at
relation.c:58
#25 0x00005e57e85a16c8 in table_open (relationId=3D464701, lockmode=3D4) at
table.c:44
#26 0x00005e57e877c41b in QueueFKConstraintValidation
(wqueue=3D0x7ffe0d13d128, conrel=3D0x76299e17b6d0, fkrel=3D0x7629895039e8,
pkrelid=3D16385,
    contuple=3D0x5e5850492148, lockmode=3D4) at tablecmds.c:13080
#27 0x00005e57e877c450 in QueueFKConstraintValidation
(wqueue=3D0x7ffe0d13d128, conrel=3D0x76299e17b6d0, fkrel=3D0x762989503268,
pkrelid=3D16385,
    contuple=3D0x5e5850491c98, lockmode=3D4) at tablecmds.c:13086
#28 0x00005e57e877c450 in QueueFKConstraintValidation
(wqueue=3D0x7ffe0d13d128, conrel=3D0x76299e17b6d0, fkrel=3D0x762989502ae8,
pkrelid=3D16385,
    contuple=3D0x5e58504917e8, lockmode=3D4) at tablecmds.c:13086
...
#37383 0x00005e57e877c450 in QueueFKConstraintValidation
(wqueue=3D0x7ffe0d13d128, conrel=3D0x76299e17b6d0, fkrel=3D0x76299dd9b218,
pkrelid=3D16385,
    contuple=3D0x5e580f357b98, lockmode=3D4) at tablecmds.c:13086
#37384 0x00005e57e877c450 in QueueFKConstraintValidation
(wqueue=3D0x7ffe0d13d128, conrel=3D0x76299e17b6d0, fkrel=3D0x76299dd98358,
pkrelid=3D16385,
    contuple=3D0x5e580f35d628, lockmode=3D4) at tablecmds.c:13086
#37385 0x00005e57e877c025 in ATExecValidateConstraint
(wqueue=3D0x7ffe0d13d128, rel=3D0x76299dd98358, constrName=3D0x5e580f3554d8=
 "fk",
recurse=3Dtrue,
    recursing=3Dfalse, lockmode=3D4) at tablecmds.c:12966
#37386 0x00005e57e876acde in ATExecCmd (wqueue=3D0x7ffe0d13d128,
tab=3D0x5e580f354fc8, cmd=3D0x5e580f355488, lockmode=3D4, cur_pass=3DAT_PAS=
S_MISC,
    context=3D0x7ffe0d13d320) at tablecmds.c:5497
#37387 0x00005e57e876a347 in ATRewriteCatalogs (wqueue=3D0x7ffe0d13d128,
lockmode=3D4, context=3D0x7ffe0d13d320) at tablecmds.c:5334
#37388 0x00005e57e876968c in ATController (parsetree=3D0x5e580f32aa88,
rel=3D0x76299dd98358, cmds=3D0x5e580f32aa38, recurse=3Dtrue, lockmode=3D4,
context=3D0x7ffe0d13d320)
    at tablecmds.c:4889
#37389 0x00005e57e876929d in AlterTable (stmt=3D0x5e580f32aa88, lockmode=3D=
4,
context=3D0x7ffe0d13d320) at tablecmds.c:4544
#37390 0x00005e57e8ae8380 in ProcessUtilitySlow (pstate=3D0x5e580f354470,
pstmt=3D0x5e580f32ab38,
    queryString=3D0x5e580f329f60 "ALTER TABLE tp0 VALIDATE CONSTRAINT fk;",
context=3DPROCESS_UTILITY_TOPLEVEL, params=3D0x0, queryEnv=3D0x0,
dest=3D0x5e580f32aef8,
    qc=3D0x7ffe0d13d980) at utility.c:1321

Reproduced on REL_18_STABLE, starting from b663b9436, and on master.