Re: [Bizgres-general] WAL bypass for INSERT, UPDATE and

Simon Riggs wrote:
> On Thu, 2005-12-29 at 11:37 -0500, Bruce Momjian wrote:
> > Having COPY behave differently because it is
> > in a transaction is fine as long as it is user-invisible, but once you
> > require users to do that to get the speedup, it isn't user-invisible
> > anymore.
>
> Since we're agreed on adding ALTER TABLE rather than COPY LOCK, we have
> our explicit mechanism for speedup.
>
> However, it costs a single line of code and very very little execution
> time to add in the optimization to COPY to make it bypass WAL when
> executed in the same transaction that created the table. Everything else
> is already there.
>
> As part of the use_wal test:
> + if (resultRelInfo->ri_NumIndices == 0 &&
> + !XLogArchivingActive() &&
> >> (cstate->rel->rd_createSubid != InvalidSubTransactionId ))
> + use_wal = false;
>
> the value is already retrieved from cache...
>
> Can anyone see a reason *not* to put that change in also? We just don't
> advertise it as the "suggested" route to gaining performance, nor would
> we rely on it for pg_dump/restore performance.

Seems like a nice optimization.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073