Re: Performance with partitions/inheritance and multiple tables

Radhika,

If the data is 9 million rows, then I would suggest that you leave it as it is, unless the server configuration and the
numberof users firing queries simultaneously is a matter of concern. 

Try creating indexes on often used fields and use EXPLAIN to speed performance of the queries ... and of course proper
configurationof autovacuum. I have seen query results within a few ms. on similar amount of data on a 2GB RHEL RAID 5
system,so it should not have been an issue. 

HTH,

Shrirang Chitnis
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From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Radhika S
Sent: Thursday, December 24, 2009 8:12 PM
To: pgsql-performance@postgresql.org
Subject: [PERFORM] Performance with partitions/inheritance and multiple tables

Hi,
We currently have a large table (9 million rows) of which only the last couple of days worth of data is queried on a
regularbasis. 
To improve performance we are thinking of partitioning the table.

One idea is:
Current_data = last days worth
archive_data < today (goes back to 2005)

The idea being proposed at work is:
current_data = today's data
prior years data - be broken down into one table per day
archive_data - data older than a year.

My question is:
a) Does postgres suffer a performance hit say if there are 200 child tables.
b) What about aggregation between dates in the last year. eg total sales for firm a  for the last year. It will need to
lookup n number of tables. 

Any ideas, tips, gotchas in implementing partitioning would be welcome. It is a somewhat mission critical (not trading,
sonot as mission critical) system. 

How expensive is maintaining so many partitions both in terms of my writing / maintaining scripts and performance.

Thanks in advance.
Radhika

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