Re: [HACKERS] The dangers of "-F" - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] The dangers of "-F"
Date
Msg-id 21070.930147026@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] The dangers of "-F"  (Philip Warner <pjw@rhyme.com.au>)
List pgsql-hackers
Philip Warner <pjw@rhyme.com.au> writes:
> Is there any chance each database could be setup differently? Some of
> my databases are updated once a month (literally), while others are
> updated daily. It would be nice to have the -F setting on the
> read-mostly DBs...

I don't think this is practical, because all the backends in a given
installation will be sharing the same buffer cache and the same pg_log
file; you can't run some with -F and some without and expect to get
the behavior you want.  Problem is that any of the backends might be
the one that writes out a particular disk block from cache.

You could run the two sets of databases as different installations
(ie, two postmasters, two listen ports, two working directories)
but that'd require all your clients knowing which port to connect to
for each database; probably not worth the trouble.

In practice, if you have a reliable OS, reliable hardware, and a
reliable power supply (read UPS), I think the risks introduced by
running with -F are negligible compared to other sources of trouble
(ie backend bugs)...
        regards, tom lane


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