Re: [HACKERS] pg_dump and thousands of schemas

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Denis <socsam(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: [HACKERS] pg_dump and thousands of schemas
Date: 2012-11-09 20:47:37
Message-ID: CAMkU=1xZbfCJL1+GrjMBXqDxtBAEvAEpk6-6tUaKM6_wRdiRRg@mail.gmail.com
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On Thu, Nov 8, 2012 at 1:04 AM, Denis <socsam(at)gmail(dot)com> wrote:
>
> Still I can't undesrtand why pg_dump has to know about all the tables?

Strictly speaking it probably doesn't need to. But it is primarily
designed for dumping entire databases, and the efficient way to do
that is to read it all into memory in a few queries and then sort out
the dependencies, rather than tracking down every dependency
individually with one or more trips back to the database. (Although
it still does make plenty of trips back to the database per
table/sequence, for acls, defaults, attributes.

If you were to rewrite pg_dump from the ground up to achieve your
specific needs (dumping one schema, with no dependencies between to
other schemata) you could probably make it much more efficient. But
then it wouldn't be pg_dump, it would be something else.

Cheers,

Jeff

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