On Wednesday, February 15, 2012 10:38:23 AM Venkat Balaji wrote:
> On Wed, Feb 15, 2012 at 12:21 PM, Scott Marlowe
<scott.marlowe@gmail.com>wrote:
> > On Tue, Feb 14, 2012 at 10:57 PM, Venkat Balaji <venkat.balaji@verse.in>
> > > all of these 1000 files get filled up in less than 5 mins, there are
> > > chances that system will slow down due to high IO and CPU.
> > As far as I know there is no data loss issue with a lot of checkpoint
> > segments.
> Data loss would be an issue when there is a server crash or pg_xlog crash
> etc. That many number of pg_xlog files (1000) would contribute to huge data
> loss (data changes not synced to the base are not guaranteed). Of-course,
> this is not related to the current situation. Normally we calculate the
> checkpoint completion time, IO pressure, CPU load and the threat to the
> data loss when we configure checkpoint_segments.
I think you might be misunderstanding something. A high number of
checkpoint_segments can lead to slower recovery - all those changes need to be
reapplied - but it won't lead to lost data. The data inside the wal will be
fsynced at appropriate times (commit; background writer; too much written).
Andres
