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shared_buffers/SHMMAX defaults?

From: Martin Pitt <mpitt(at)debian(dot)org>
To: PostgreSQL Bugs <pgsql-bugs(at)postgresql(dot)org>
Subject: shared_buffers/SHMMAX defaults?
Date: 2009-03-30 14:34:36
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Hello fellow PostgreSQL packagers,

recently, I started to get quite a bunch of bug reports a la
"PostgreSQL fails to start due to too little shared memory" [1]. I
have never seen this before, neither in Debian, so I guess the
SHMMAX defaults changed somewhat in Linux 2.6.27. It seems that with
other components, such as, using large amounts of shared memory
as well, startup sometimes works and sometimes doesn't.

Now I wonder what I should do about it. I see these options:

(1) Ignore
    + no hidden magic
    - very inconvenient, package installation does not create default
      cluster sometimes, or the default cluster fails to start on
      system boot

   Best solution for admin control freaks.

(2) Be more conservative about initdb's default setting
    + no hidden magic
    + upstream compatible solution
    - suboptimal performance by default

(3) Change SHMMAX in postgresql's init script if necessary
    + Always works
    - Unexpected, works behind admin's back.

Currently I tend towards (2), but I'd like to hear some more opinions
about it.

Does anyone else have seen this problem as well?




Martin Pitt                        |
Ubuntu Developer (  | Debian Developer  (


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Next:From: Tom LaneDate: 2009-03-31 00:29:37
Subject: Re: shared_buffers/SHMMAX defaults?
Previous:From: Brice Maron & Duchesne P-ADate: 2009-03-30 14:20:24
Subject: BUG #4741: Domain constraint violation with trigger

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