Re: xlogdump fixups and WAL log question.

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

> Theo Schlossnagle  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/