From: M Simms <grim@argh.demon.co.uk>
To: pgsql-general@postgreSQL.org
Subject: A few questions
Date: Mon, 12 Jul 1999 02:30:58 +0100 (BST)
Message-ID: <199907120130.CAA07664@argh.demon.co.uk> (raw)
Hi
I asked these questions a couple of weeks ago and got no response whatsoever
so I am going to try again.
I have just installed 6.5, and there are some things I cannot find in
the documentation.
1 ) When I use temp tables, is there a way to instruct postgresql to
keep these in memory rather than on disc, for faster access, or
does it do this anyway with temp tables
2 ) Is there an optimal amount of updates and inserts to perform
before vacuuming a database, some kind of formula based on inserts
and updates that indicates when a vacuum would be most
beneficial. I realise there cannot be an absolute rule for this,
but a guideline would help, as I dont know if I will need to
vacuum more than once a day on a busy database.
3 ) Is there a way to instruct postgresql to perform a query at a
lower priority, such as daily maintainence operations, so that
these jobs do not impact on the interactive actions. I realise
I can renice a process that is making calls to the database, but
that doesnt have any effect on the backend spawned by the
postmaster when I connect to it.
If there is no such functionality, would people be interested in it
if I was to code it and release it back to the main source tree?
4 ) Is there an optimal ratio between the number of backends and the
number of shared memory buffers. I realise there is a minimum of
1:2 but do more shared memory buffers increase performance in some
areas, or would the extra overhead of managing the buffers make the
increase pointless.
5 ) The final question (I promise) is that if I have a large number of
inserts that I generate dynamically, is it quicker for me to
perform these inserts one by one (maybee 10,000 of them at a time)
or would it be faster and less CPU intensive to generate a text
file instead and then read this in via a single copy command.
This file at times may be over 100,000 entries, so would I be
better to split it to a maximum number of transactions if I
take the route of the copy command?
Thanks in advance, and I hope that this time someone will be able
to answer some or all of these questions.
M Simms
PS. Appologies to the person that receives this twice, I hit reply
instead of group reply to your mail to this list, and so you got
yourown personal copy {:-)
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To: pgsql-general@postgresql.org
Cc: grim@argh.demon.co.uk
Subject: Re: A few questions
In-Reply-To: <199907120130.CAA07664@argh.demon.co.uk>
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