Re: pg_dumpall affecting performance

I was always under the impression that pg_dump and pg_dumpall cause all data to be read in to the buffers and then out, (of course squeezing out whatever may be active). That is the big advantage to using PITR backups and using a tar or cpio method of backing up active containers and shipping off to another system, disk or api to tape system.

-----Original Message-----
From: pgsql-performance-owner(at)postgresql(dot)org [mailto:pgsql-performance-owner(at)postgresql(dot)org] On Behalf Of Mark Mikulec
Sent: Tuesday, February 15, 2011 12:41 PM
To: pgsql-performance(at)postgresql(dot)org
Subject: [PERFORM] pg_dumpall affecting performance

Hello,

I was under the impression that pg_dumpall didn't affect database performance when dumping while the db is live. However I have evidence to the contrary now - queries that are run during the pg_dumpall time take 10 to a 100 times longer to execute than normal while pg_dumpall is running.
The strange thing is that this started after my database grew by about 25% after a large influx of data due to user load. I'm wonder if there is a tipping point or a config setting I need to change now that the db is larger that is causing all this to happen.

Thanks,
Mark

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