Re: xlogdump fixups and WAL log question.

On Oct 20, 2006, at 1:58 PM, Tom Lane wrote:

> Theo Schlossnagle <jesus(at)omniti(dot)com> writes:
>> Is it possible to create tables in fashion that will not write info
>> to the WAL log -- knowingly and intentionally making them
>> unrecoverable?
>
> Use temp tables?

temp tables won't work too well -- unless I can make a whole
tablespace "temp" and multiple backends can see it. They work fine
for small tables we snapshot (couple hundred or even a few thousand
rows), but many of the tables are a few hundred thousand rows and
several processes on the system all need them.

> Also, it's likely that much of the WAL volume is full-page images.
> While you can't safely turn those off in 8.1, you can dial down the
> frequency of occurrence by increasing checkpoint_segments and
> checkpoint_timeout as much as you can stand. (The tradeoffs are
> amount of space occupied by pg_xlog/ and time to recover from a
> crash.)

Our pg_xlog is currently at 9.6GB. Not sure I can reasonably tune it
up much higher.

// Theo Schlossnagle
// CTO -- http://www.omniti.com/~jesus/
// OmniTI Computer Consulting, Inc. -- http://www.omniti.com/