On Fri, Jul 03, 2015 at 12:21:02AM +0200, Andres Freund wrote: > Hi, > > On 2015-07-03 00:05:24 +0200, Martijn van Oosterhout wrote: > > === Start with an empty database > > My guess is you have wal_level = minimal?
Default config, was just initdb'd. So yes, the default wal_level = minimal. > > === Note the index file is 8KB. > > === At this point nuke the database server (in this case it was simply > > === destroying the container it was running in. > > How did you continue from there? The container has persistent storage? > Or are you repapplying the WAL to somewhere else? The container has persistant storage on the host. What I think is actually unusual is that the script that started postgres was missing an 'exec" so postgres never gets the signal to shutdown. > > martijn@martijn-jessie:$ sudo /usr/lib/postgresql/9.4/bin/pg_xlogdump -p > > /data/postgres/pg_xlog/ 000000010000000000000001 |grep -wE > > '16389|16387|16393' > > rmgr: XLOG len (rec/tot): 72/ 104, tx: 0, lsn: > > 0/016A9240, prev 0/016A9200, bkp: 0000, desc: checkpoint: redo 0/16A9240; > > tli 1; prev tli 1; fpw true; xid 0/686; oid 16387; multi 1; offset 0; > > oldest xid 673 in DB 1; oldest multi 1 in DB 1; oldest running xid 0; > > shutdown > > rmgr: Storage len (rec/tot): 16/ 48, tx: 0, lsn: > > 0/016A92D0, prev 0/016A92A8, bkp: 0000, desc: file create: base/16385/16387 > > rmgr: Sequence len (rec/tot): 158/ 190, tx: 686, lsn: > > 0/016B5E50, prev 0/016B5D88, bkp: 0000, desc: log: rel 1663/16385/16387 > > rmgr: Storage len (rec/tot): 16/ 48, tx: 686, lsn: > > 0/016B5F10, prev 0/016B5E50, bkp: 0000, desc: file create: base/16385/16389 > > rmgr: Storage len (rec/tot): 16/ 48, tx: 686, lsn: > > 0/016BB028, prev 0/016BAFD8, bkp: 0000, desc: file create: base/16385/16393 > > rmgr: Sequence len (rec/tot): 158/ 190, tx: 686, lsn: > > 0/016BE4F8, prev 0/016BE440, bkp: 0000, desc: log: rel 1663/16385/16387 > > rmgr: Storage len (rec/tot): 16/ 48, tx: 686, lsn: > > 0/016BE6B0, prev 0/016BE660, bkp: 0000, desc: file truncate: > > base/16385/16389 to 0 blocks > > rmgr: Storage len (rec/tot): 16/ 48, tx: 686, lsn: > > 0/016BE6E0, prev 0/016BE6B0, bkp: 0000, desc: file truncate: > > base/16385/16393 to 0 blocks > > pg_xlogdump: FATAL: error in WAL record at 0/16BE710: record with zero > > length at 0/16BE740 > > Note that the truncate will lead to a new, different, relfilenode. Really? Comparing the relfilenodes gives the same values before and after the truncate. > > > ctmp=# select * from test; > > ERROR: could not read block 0 in file "base/16385/16393": read only 0 of > > 8192 bytes > > Hm. I can't reproduce this. Can you include a bit more details about how > to reproduce? Hmm, for me it is 100% reproducable. Are you familiar with Docker? I can probably construct a Dockerfile that reproduces it pretty reliably. Have a nice day, -- Martijn van Oosterhout <klep...@svana.org> http://svana.org/kleptog/ > He who writes carelessly confesses thereby at the very outset that he does > not attach much importance to his own thoughts. -- Arthur Schopenhauer
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