Re: wal sync method - Mailing list pgsql-performance

From PFC
Subject Re: wal sync method
Date
Msg-id op.s5qgvjilcigqcu@apollo13
Whole thread Raw
In response to Re: wal sync method  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance

    Hm, i seem to have mixed fwrite() (which buffers data in userspace) and
write() (which apparently doesnt !)
    Sorry !

> PFC <lists@peufeu.com> writes:
>>     Just a stupid question about the various fsync settings.
>>     There is fsync=off, but is there fsync=fflush ?
>>     fflush would mean only an OS crash could cause data loss,
>>     I think.it could be useful for some applications where you need a speed
>> boost (like testing database import scripts...) without being as scary
>> as
>> fsync=off...
>
> I think you misunderstand.  There aren't any scenarios where a PG crash
> (without hardware/OS crash) risks data, because we always at least
> write() data before commit.  The only issue is how hard do we try to get
> the OS+hardware to push that data down to disk.
>
>             regards, tom lane



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