From: Tom Lane <tgl@sss.pgh.pa.us>
To: Denis <socsam@gmail.com>
cc: pgsql-performance@postgresql.org
Subject: Re: [HACKERS] pg_dump and thousands of schemas
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Comments: In-reply-to Denis <socsam@gmail.com>
	message dated "Wed, 07 Nov 2012 02:42:52 -0800"
Date: Wed, 07 Nov 2012 10:02:37 -0500
Message-ID: <8407.1352300557@sss.pgh.pa.us>

Denis <socsam@gmail.com> writes:
> Tom Lane-2 wrote
>> Hmmm ... so the problem here isn't that you've got 2600 schemas, it's
>> that you've got 183924 tables.  That's going to take some time no matter
>> what.

> I wonder why pg_dump has to have deal with all these 183924 tables, if I
> specified to dump only one scheme: "pg_dump -n schema_name" or even like
> this to dump just one table "pg_dump -t 'schema_name.comments' "  ?

It has to know about all the tables even if it's not going to dump them
all, for purposes such as dependency analysis.

> We have a web application where we create a schema with a number of tables
> in it for each customer. This architecture was chosen to ease the process of
> backup/restoring data.

I find that argument fairly dubious, but in any case you should not
imagine that hundreds of thousands of tables are going to be cost-free.

			regards, tom lane