Date: Mon, 15 Oct 2012 13:59:16 -0700 (PDT)
From: houmanb <houman@gmx.at>
To: pgsql-performance@postgresql.org
Message-ID: <1350334756457-5728306.post@n5.nabble.com>
Subject: SELECT AND AGG huge tables
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Dear all,
We have a DB containing transactional data. 
There are about *50* to *100 x 10^6* rows in one *huge* table.
We are using postgres 9.1.6 on linux with a *SSD card on PCIex* providing us
a constant seeking time.

A typical select (see below) takes about 200 secs. As the database is the
backend for a web-based reporting facility 200 to 500 or even more secs
response times are not acceptable for the customer.

Is there any way to speed up select statements like this:

SELECT
   SUM(T.x),
   SUM(T.y),
   SUM(T.z),
   AVG(T.a),
   AVG(T.b)
FROM T
GROUP BY 
   T.c
WHERE 
   T.creation_date=$SOME_DATE;

There is an Index on T.c. But would it help to partition the table by T.c?
It should be mentioned, that T.c is actually a foreign key to a Table
containing a 
tiny number of rows (15 rows representing different companies).
my postgres.conf is actually the default one, despite the fact that we
increased the value for work_mem=128MB

Thanks in advance
Houman


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