Re: pglz performance
От | Tomas Vondra |
---|---|
Тема | Re: pglz performance |
Дата | |
Msg-id | 20190804173004.ovg6tsf336teyy57@development обсуждение исходный текст |
Ответ на | Re: pglz performance (Petr Jelinek <petr@2ndquadrant.com>) |
Список | pgsql-hackers |
On Sun, Aug 04, 2019 at 05:53:26PM +0200, Petr Jelinek wrote: > > ... > >> >>4) I did a simple test with physical replication, with lz4 enabled on >>both sides (well, can't build without lz4 anyway, per previous point). >>It immediately failed like this: >> >>FATAL: failed to restore block image >>CONTEXT: WAL redo at 0/5000A40 for Btree/INSERT_LEAF: off 138 >>LOG: startup process (PID 15937) exited with exit code 1 >> >>This is a simple UPDATE on a trivial table: >> >>create table t (a int primary key); >>insert into t select i from generate_series(1,1000) s(i); >>update t set a = a - 100000 where random () < 0.1; >> >>with some checkpoints to force FPW (and wal_compression=on, of course). >> >>I haven't tried `make check-world` but I suppose some of the TAP tests >>should fail because of this. And if not, we need to improve coverage. >> > >FWIW I did run check-world without problems, will have to look into this. > Not sure if we bother to set wal_compression=on for check-world (I don't think we do, but I may be missing something), so maybe check-world does not really test wal compression. IMO the issue is that RestoreBlockImage() still calls pglz_decompress directly, instead of going through pg_decompress(). regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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