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.

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