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Re: [PERFORM] BUG #4919: CREATE USER command slows down system performance

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, toruvinn <toruvinn(at)lain(dot)pl>, pgsql-bugs(at)postgresql(dot)org, pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] BUG #4919: CREATE USER command slows down system performance
Date: 2009-08-08 20:31:45
Message-ID: 200908082031.n78KVje23903@momjian.us (view raw or flat)
Thread:
Lists: pgsql-bugspgsql-performance
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Tom Lane wrote:
> >> Now that we have SQL-level CONNECT privilege, I wonder just how much
> >> functionality would be lost if we got rid of the flat files and told
> >> people they had to use CONNECT to do any per-user or per-database
> >> access control.
> >> 
> >> The main point I can see offhand is that password checking would have
> >> to be done a lot later in the startup sequence, with correspondingly
> >> more cycles wasted to reject bad passwords.
> 
> > Is this a TODO?
> 
> Well, it's a TO-THINK-ABOUT anyway.  I think the appropriate next step
> would not be to write code, but to do a detailed investigation of what
> would be gained or lost.  I don't remember exactly what we do with the
> flat-file contents.

The flat file is the username/password sorted list.  We load that info
into the postmaster in an array that we can binary sort.

I wonder how big the postmaster process address space was when handling
2 billion users:

	http://archives.postgresql.org/pgsql-bugs/2009-07/msg00176.php

It seems just storing many users in the postmaster could be burdensome,
but fixing that would be creating something like a database, which we
already have.  ;-)

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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