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Subject: BUG #19551: TRAP: failed Assert("max_pinned_buffers > 0")
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: r.zharkov@postgrespro.ru
Reply-To: r.zharkov@postgrespro.ru, pgsql-bugs@lists.postgresql.org
Date: Fri, 10 Jul 2026 07:36:39 +0000
Message-ID: <19551-d4a55b8fe81db4f2@postgresql.org>
Auto-Submitted: auto-generated
Archived-At: 
 <https://www.postgresql.org/message-id/19551-d4a55b8fe81db4f2%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19551
Logged by:          Roman Zharkov
Email address:      r.zharkov@postgrespro.ru
PostgreSQL version: 17.10
Operating system:   WSL2 on Windows 11
Description:       =20

Hello,
This error occurred when attempting run the temp.sql regression test from
the master branch on the REL_17_STABLE (#bab0a2db).
It seems, REL_16_STABLE and REL_18_STABLE work fine.

Trimmed script:
SET temp_buffers =3D 100;

CREATE TEMPORARY TABLE test_temp(a int not null unique, b TEXT not null, cnt
int not null);
INSERT INTO test_temp SELECT generate_series(1, 10000) as id, repeat('a',
200), 0;
-- should be at least 2x as large than temp_buffers
SELECT pg_relation_size('test_temp') / current_setting('block_size')::int8 >
200;

-- Don't want cursor names and plpgsql function lines in the error messages
\set VERBOSITY terse

/* helper function to create cursors for each page in [p_start, p_end] */
CREATE FUNCTION test_temp_pin(p_start int, p_end int)
RETURNS void
LANGUAGE plpgsql
AS $f$
  DECLARE
      cursorname text;
      query text;
  BEGIN
    FOR i IN p_start..p_end LOOP
       cursorname =3D 'c_'||i;
       query =3D format($q$DECLARE %I CURSOR FOR SELECT ctid FROM test_temp
WHERE ctid >=3D '( %s, 1)'::tid $q$, cursorname, i);
       EXECUTE query;
       EXECUTE 'FETCH NEXT FROM '||cursorname;
       -- for test development
       -- RAISE NOTICE '%: %', cursorname, query;
    END LOOP;
  END;
$f$;


-- Test overflow of temp table buffers is handled correctly
BEGIN;
-- should work, below max
SELECT test_temp_pin(0, 9);
-- should fail, too many buffers pinned
SELECT test_temp_pin(10, 105);
ROLLBACK;


Backtrace:
=E2=80=A6
#5  0x0000643754e9190c in ExceptionalCondition (conditionName=3D0x6437550cc=
f79
"max_pinned_buffers > 0", fileName=3D0x6437550cccf0
"/home/roman/git/connpool_build/build/../../connpool/src/backend/storage/ai=
o/read_stream.c",
lineNumber=3D473)
    at
/home/roman/git/connpool_build/build/../../connpool/src/backend/utils/error=
/assert.c:66
#6  0x0000643754c37a4f in read_stream_begin_relation (flags=3D2, strategy=
=3D0x0,
rel=3D0x7179e34caf78, forknum=3DMAIN_FORKNUM, callback=3D0x64375471e46b
<heap_scan_stream_read_next_serial>, callback_private_data=3D0x6437817b95a8,
per_buffer_data_size=3D0)
    at
/home/roman/git/connpool_build/build/../../connpool/src/backend/storage/aio=
/read_stream.c:473
#7  0x000064375471f92d in heap_beginscan (relation=3D0x7179e34caf78,
snapshot=3D0x64378169b868, nkeys=3D0, key=3D0x0, parallel_scan=3D0x0, flags=
=3D272) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/access/heap=
/heapam.c:1185
#8  0x0000643754a1df61 in table_beginscan_tidrange (rel=3D0x7179e34caf78,
snapshot=3D0x64378169b868, mintid=3D0x6437817b87e0, maxtid=3D0x6437817b87e6=
) at
/home/roman/git/connpool_build/build/../../connpool/src/include/access/tabl=
eam.h:1097
#9  0x0000643754a1e787 in TidRangeNext (node=3D0x6437817b86f8) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/no=
deTidrangescan.c:243
#10 0x00006437549d23cc in ExecScanFetch (node=3D0x6437817b86f8,
accessMtd=3D0x643754a1e6d8 <TidRangeNext>, recheckMtd=3D0x643754a1e805
<TidRangeRecheck>) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/ex=
ecScan.c:139
#11 0x00006437549d2471 in ExecScan (node=3D0x6437817b86f8,
accessMtd=3D0x643754a1e6d8 <TidRangeNext>, recheckMtd=3D0x643754a1e805
<TidRangeRecheck>) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/ex=
ecScan.c:205
#12 0x0000643754a1e8ff in ExecTidRangeScan (pstate=3D0x6437817b86f8) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/no=
deTidrangescan.c:308
#13 0x00006437549cdc93 in ExecProcNodeFirst (node=3D0x6437817b86f8) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/ex=
ecProcnode.c:464
#14 0x00006437549c0c12 in ExecProcNode (node=3D0x6437817b86f8) at
/home/roman/git/connpool_build/build/../../connpool/src/include/executor/ex=
ecutor.h:278
#15 0x00006437549c3b4e in ExecutePlan (queryDesc=3D0x6437816c3520,
operation=3DCMD_SELECT, sendTuples=3Dtrue, numberTuples=3D1,
direction=3DForwardScanDirection, dest=3D0x6437552bda80 <spi_printtupDR>)
    at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/ex=
ecMain.c:1689
#16 0x00006437549c12dd in standard_ExecutorRun (queryDesc=3D0x6437816c3520,
direction=3DForwardScanDirection, count=3D1, execute_once=3Dfalse) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/ex=
ecMain.c:360
#17 0x00006437549c1136 in ExecutorRun (queryDesc=3D0x6437816c3520,
direction=3DForwardScanDirection, count=3D1, execute_once=3Dfalse) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/executor/ex=
ecMain.c:306
#18 0x0000643754c9b597 in PortalRunSelect (portal=3D0x6437816c6b78,
forward=3Dtrue, count=3D1, dest=3D0x6437552bda80 <spi_printtupDR>) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/tcop/pquery=
.c:922
#19 0x0000643754c9c763 in DoPortalRunFetch (portal=3D0x6437816c6b78,
fdirection=3DFETCH_FORWARD, count=3D1, dest=3D0x6437552bda80 <spi_printtupD=
R>) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/tcop/pquery=
.c:1665
#20 0x0000643754c9c0ff in PortalRunFetch (portal=3D0x6437816c6b78,
fdirection=3DFETCH_FORWARD, count=3D1, dest=3D0x6437552bda80 <spi_printtupD=
R>) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/tcop/pquery=
.c:1416
#21 0x0000643754930f24 in PerformPortalFetch (stmt=3D0x64378153d3f0,
dest=3D0x6437552bda80 <spi_printtupDR>, qc=3D0x7ffc60e51fc0) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/commands/po=
rtalcmds.c:198
#22 0x0000643754c9d8c9 in standard_ProcessUtility (pstmt=3D0x64378153d2e0,
queryString=3D0x643781539a20 "FETCH NEXT FROM c_99", readOnlyTree=3Dtrue,
context=3DPROCESS_UTILITY_QUERY, params=3D0x0, queryEnv=3D0x0, dest=3D0x643=
7552bda80
<spi_printtupDR>,
    qc=3D0x7ffc60e51fc0) at
/home/roman/git/connpool_build/build/../../connpool/src/backend/tcop/utilit=
y.c:703
=E2=80=A6