From: Bruce Momjian <bruce@momjian.us>
Message-Id: <200708270249.l7R2nfX00882@momjian.us>
Subject: Re: Block size with pg_dump?
In-Reply-To: <5539298E-EF2B-4CA2-8BFB-6D8656E05610@myemma.com>
To: Erik Jones <erik@myemma.com>
Date: Sun, 26 Aug 2007 22:49:41 -0400 (EDT)
CC: Jean-David Beyer <jeandavid8@verizon.net>, pgsql-sql@postgresql.org
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Erik Jones wrote:
> >>> On the way back, likewise I could pipe the tape through dd before  
> >>> giving it
> >>> to pg_restore.
> >>>
> >>> Does pg_dump care what blocksize it gets? If so, what is it?
> >>
> >> I assume you could pipe pg_dump into dd and specify the block size in
> >> dd.
> >>
> > Of course on the way out I can do that.
> >
> > The main question is, If I present pg_restore with a 65536-byte  
> > blocksize
> > and it is expecting, e.g., 1024-bytes, will the rest of each block get
> > skipped? I.e., do I have to use dd on the way back too? And if so,  
> > what
> > should the blocksize be?
> 
> Postgres (by default) uses 8K blocks.

That is true of the internal storage, but not of pg_dump's output
because it is using libpq to pull rows and output them in a stream,
meaning there is no blocking in pg_dumps output itself.

-- 
  Bruce Momjian  <bruce@momjian.us>          http://momjian.us
  EnterpriseDB                               http://www.enterprisedb.com

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