Re: [HACKERS] Full page writes improvement

Koichi Suzuki <suzuki(dot)koichi(at)oss(dot)ntt(dot)co(dot)jp> writes:
> Tom Lane wrote:
>> Doesn't this break crash recovery on PITR slaves?

> Compressed archive log contains the same data as full_page_writes off
> case. So the influence to PITR slaves is the same as full_page_writes off.

Right. So what is the use-case for running your primary database with
full_page_writes on and the slaves with it off? It doesn't seem like
a very sensible combination to me.

Also, it seems to me that some significant performance hit would be
taken by having to grovel through the log files to remove and re-add the
full-page data. Plus you are actually writing *more* WAL data out of
the primary, not less, because you have to save both the full-page
images and the per-tuple data they normally replace. Do you have
numbers showing that there's actually any meaningful savings overall?

regards, tom lane