Date: Mon, 27 Aug 2007 08:28:25 -0400
From: Jean-David Beyer <jeandavid8@verizon.net>
Subject: Re: Block size with pg_dump?
In-reply-to: <200708270249.l7R2nfX00882@momjian.us>
To: pgsql-sql@postgresql.org
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Organization: Institute for Regimented Whimsey
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Bruce Momjian wrote:
> 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.
> 
Is that true for both input and output (i.e., pg_restore and pg_dump)?
I.e., can I use dd to write 65536-byte blocks to tape, and then do nothing
on running pg_restore? I.e., that pg_restore will accept any block size I
choose to offer it?

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