Message-ID: <4AF63F5B.2060300@postnewspapers.com.au>
Date: Sun, 08 Nov 2009 11:47:39 +0800
From: Craig Ringer <craig@postnewspapers.com.au>
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To: Aris Samad-Yahaya <aris@quickschools.com>
CC: pgsql-performance@postgresql.org
Subject: Re: CREATE TABLE slowing down significantly over time
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On 8/11/2009 11:15 AM, Aris Samad-Yahaya wrote:

> It used to take about 15 seconds to create those 300 tables in a new
> schema (when there were only a few schemas, say about 50). It now takes
> about 3 minutes (and now we have about 200 schemas, with more data but
> not hugely so).

200 schemas, 300 tables per schema. That's sixty THOUSAND tables.

> * Is the problem caused by the increasing number of schemas?

and increasing table count, I expect.

You do batch the table and schema creation into a single transaction,
right? If not, do that first, rather than creating each table in a
separate transaction (ie: relying on autocommit).

It may also be worth thinking about the app's design. Is a new schema
and 300 new tables for each user really the best way to tackle what
you're doing? (It might be, but it's a question worth asking yourself).

--
Craig Ringer