Re: race condition in sync rep - Mailing list pgsql-hackers

From Tom Lane
Subject Re: race condition in sync rep
Date
Msg-id 4636.1301162688@sss.pgh.pa.us
Whole thread Raw
In response to Re: race condition in sync rep  (Simon Riggs <simon@2ndQuadrant.com>)
List pgsql-hackers
Simon Riggs <simon@2ndQuadrant.com> writes:
> On Sat, Mar 26, 2011 at 4:24 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Well, in that case, it should be on the open-items list. �If the system
>> is still behaving that way, it's a bug.

> Is it? Sync rep requires fsync on the standby. If you then explicitly
> turn off fsync on the standby then it has a performance impact, as
> documented.

No, that's utter nonsense.  If the system is behaving that way, then
it's a bug.  If you don't think it's a bug, then you misunderstand what
the fsync GUC is supposed to do.  What fsync=off is supposed to do is
cause every attempted fsync to succeed instantly.  It is *not possible*
for that to result in a performance slowdown compared to fsyncs that
take nonzero time.  Unless someone's broken it.  The documented behavior
is broken.  Period.
        regards, tom lane


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