| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
| Cc: | Dagfinn Ilmari Mannsåker <ilmari(at)ilmari(dot)org>, Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Stephen Frost <sfrost(at)snowman(dot)net>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, David Steele <david(at)pgmasters(dot)net>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Jakub Wartak <Jakub(dot)Wartak(at)tomtom(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: WIP: WAL prefetch (another approach) |
| Date: | 2022-04-25 18:31:48 |
| Message-ID: | 113605.1650911508@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Oh, one more bit of data: here's an excerpt from pg_waldump output after
the failed test:
rmgr: Btree len (rec/tot): 72/ 72, tx: 727, lsn: 0/01903BC8, prev 0/01903B70, desc: INSERT_LEAF off 111, blkref #0: rel 1663/16384/2673 blk 9
rmgr: Btree len (rec/tot): 72/ 72, tx: 727, lsn: 0/01903C10, prev 0/01903BC8, desc: INSERT_LEAF off 141, blkref #0: rel 1663/16384/2674 blk 7
rmgr: Standby len (rec/tot): 42/ 42, tx: 727, lsn: 0/01903C58, prev 0/01903C10, desc: LOCK xid 727 db 16384 rel 16391
rmgr: Transaction len (rec/tot): 437/ 437, tx: 727, lsn: 0/01903C88, prev 0/01903C58, desc: COMMIT 2022-04-25 20:16:03.374197 CEST; inval msgs: catcache 80 catcache 79 catcache 80 catcache 79 catcache 55 catcache 54 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 snapshot 2608 relcache 16391
rmgr: Heap len (rec/tot): 59/ 59, tx: 728, lsn: 0/01903E40, prev 0/01903C88, desc: INSERT+INIT off 1 flags 0x00, blkref #0: rel 1663/16384/16391 blk 0
rmgr: Heap len (rec/tot): 59/ 59, tx: 728, lsn: 0/01903E80, prev 0/01903E40, desc: INSERT off 2 flags 0x00, blkref #0: rel 1663/16384/16391 blk 0
rmgr: Transaction len (rec/tot): 34/ 34, tx: 728, lsn: 0/01903EC0, prev 0/01903E80, desc: COMMIT 2022-04-25 20:16:03.379323 CEST
rmgr: Heap len (rec/tot): 59/ 59, tx: 729, lsn: 0/01903EE8, prev 0/01903EC0, desc: INSERT off 3 flags 0x00, blkref #0: rel 1663/16384/16391 blk 0
rmgr: Heap len (rec/tot): 59/ 59, tx: 729, lsn: 0/01903F28, prev 0/01903EE8, desc: INSERT off 4 flags 0x00, blkref #0: rel 1663/16384/16391 blk 0
rmgr: Transaction len (rec/tot): 34/ 34, tx: 729, lsn: 0/01903F68, prev 0/01903F28, desc: COMMIT 2022-04-25 20:16:03.381720 CEST
The error is complaining about not being able to read 0/01903E40,
which AFAICT is from the first "INSERT INTO sample_tbl" command,
which most certainly ought to be down to disk at this point.
Also, I modified the test script to see what WAL LSNs it thought
it was dealing with, and got
+\echo 'wal_lsn1 = ' :wal_lsn1
+wal_lsn1 = 0/1903E40
+\echo 'wal_lsn2 = ' :wal_lsn2
+wal_lsn2 = 0/1903EE8
confirming that idea of where 0/01903E40 is in the WAL history.
So this is sure looking like a bug somewhere in xlogreader.c,
not in pg_walinspect.
regards, tom lane
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| Next Message | Stephen Frost | 2022-04-25 18:39:57 | Re: pg_walcleaner - new tool to detect, archive and delete the unneeded wal files (was Re: pg_archivecleanup - add the ability to detect, archive and delete the unneeded wal files on the primary) |
| Previous Message | Tom Lane | 2022-04-25 18:11:49 | Re: WIP: WAL prefetch (another approach) |