On Apr 3, 2008, at 7:08 PM, Andrew Dunstan wrote:
Joshua D. Drake wrote:
Theo Schlossnagle wrote:
First whack at exposing the start and finish checkpoint times into
SQL.
Why is that useful?
For knowing how long checkpoints are taking. If they are taking too
long you may need to adjust your bgwriter settings, and it is a
serious drag to parse postgresql logs for this info.
Even if this were true, surely the answer is to improve the logging.
Has this feature been discussed on -hackers? I don't recall it (and
my memory has plenty of holes in it), but I'm sure that after
attending my talk last Sunday Theo hasn't sent in a patch for an
undiscussed feature ;-)
Andrew: I don't think this feature has been discussed on hackers. The
patch took about 15 minutes to author, so it sounds like the most
concise way to start a conversation. Seems silly to start the
conversation on hackers with a patch. :-)
Alvaro: Thanks, I flip that to GetCurrentTimestamp()
Heikki: It it useful for knowing when the last checkpoint occurred.
Like Robert, we have situations where reading the log file is a PITA
-- so this provides that information. I originally planned on only
adding the start time, but figured adding the end would make sense too.
Tom: It worked for me in my testing, though I did not extensively
tested. I didn't see anywhere the stats are zero'd out, so I believe
the timestamp is zero at start and then only ever set to the starttime
during a checkpoint invocation. I admittedly don't have a thorough
understanding of that code -- but that segment (before my patch)
looked pretty concise.
--
Theo Schlossnagle
Esoteric Curio -- http://lethargy.org/
OmniTI Computer Consulting, Inc. -- http://omniti.com/
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