Message-ID: <509C9F91.4020902@2ndQuadrant.com>
Date: Fri, 09 Nov 2012 14:15:45 +0800
From: Craig Ringer <craig@2ndQuadrant.com>
Organization: 2nd Quadrant
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To: Denis <socsam@gmail.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Thousands databases or schemas
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On 11/08/2012 09:29 PM, Denis wrote:
> Ok guys, it was not my intention to hurt anyone's feelings by mentioning
> MySQL. Sorry about that.
It's pretty silly to be upset by someone mentioning another DB product.
I wouldn't worry.
> There simply was a project with a similar
> architecture built using MySQL. When we started the current project, I have
> made a decision to give PostgreSQL a try.
It's certainly interesting that MySQL currently scales to much larger
table counts better than PostgreSQL appears to.

I'd like to see if this can be improved down the track. Various people
are doing work on PostgreSQL scaling and performance, so with luck huge
table counts will come into play there. If nothing else, supporting
large table counts is important when dealing with very large amounts of
data in partitioned tables.

I think I saw mention of better performance with higher table counts in
9.3 in -hackers, too.

> I would recommend you to refresh the info here 
> http://wiki.postgresql.org/wiki/FAQ. There is a question "What is the
> maximum size for a row, a table, and a database?". Please add there info on
> maximum DBs number and tables number one DB can contain while PostgreSQL
> continues to work properly.
Yeah, a number of people have been thrown by that. Technical limitations
aren't the same as practical limitations, and in some cases the
practical limitations are lower.

The trouble is: How do you put a number to it when something is a slow
and gradual drop in performance? And when one person's "performs
adequately" is another's "way too slow" ?

--
Craig Ringer