From: Alexy Khrabrov <deliverable@gmail.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: two memory-consuming postgres processes
Date: Fri, 2 May 2008 13:51:44 -0700
Message-ID: <EFF7D449-2965-4BAB-B127-387744C9CEDD@gmail.com> (raw)
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On May 2, 2008, at 1:40 PM, Scott Marlowe wrote:
> Again, a database protects your data from getting scrambled should the
> program updating it quit halfway through etc...
Right -- but this is a data mining work, I add a derived column to a
row, and it's computed from that very row and a small second table
which should fit in RAM.
> Have you been vacuuming between these update attempts? Each one has
> created millions of dead rows and bloated your data store. vacuum
> full / cluster / reindex may be needed.
I've read postgresql.conf better and see autovacuum = on is commented
out, so it's on. That explains why shutting down was taking so long
to shut autovacuum down too.
Basically, the derived data is not critical at all, -- can I turn (1)
off transactional behavior for an UPDATE, (2) should I care about
vacuuming being done on the fly when saving RAM, or need I defer it/
manage it manually?
I wonder what MySQL would do here on MyISAM tables without
transactional behavior -- perhaps this is the case more suitable for
them?
Cheers,
Alexy
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To: pgsql-performance@postgresql.org
Cc: deliverable@gmail.com, scott.marlowe@gmail.com, tgl@sss.pgh.pa.us
Subject: Re: two memory-consuming postgres processes
In-Reply-To: <EFF7D449-2965-4BAB-B127-387744C9CEDD@gmail.com>
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