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Re: Maximum number of sequences that can be created

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Craig James <cjames(at)emolecules(dot)com>
Cc: Віталій Тимчишин <tivv00(at)gmail(dot)com>, Robert Klemme <shortcutter(at)googlemail(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Maximum number of sequences that can be created
Date: 2012-05-14 22:50:05
Message-ID: CAMkU=1z0vUzB8i+gcVhisEh8jv-2UZJPRm_T00sEj7v=wGV04Q@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Sun, May 13, 2012 at 9:01 AM, Craig James <cjames(at)emolecules(dot)com> wrote:
>
> In my experience (PG 8.4.x), the system can handle in the neighborhood of
> 100,000 relations pretty well.  Somewhere over 1,000,000 relations, the
> system becomes unusable.  It's not that it stops working -- day-to-day
> operations such as querying your tables and running your applications
> continue to work.  But system operations that have to scan for table
> information seem to freeze (maybe they run out of memory, or are
> encountering an O(N^2) operation and simply cease to complete).
>
> For example, pg_dump fails altogether.  After 24 hours, it won't even start
> writing to its output file.  The auto-completion in psql of table and column
> names freezes the system.  It takes minutes to drop one table.  Stuff like
> that. You'll have a system that works, but can't be backed up, dumped,
> repaired or managed.
>
> As I said, this was 8.4.x. Things may have changed in 9.x.

I think some of those things might have improved, but enough of them
have not improved, or not by enough.

So I agree with your assessment, under 9.2 having millions of
sequences might technically work, but would render the database
virtually unmanageable.

Cheers,

Jeff

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