Re: pgbench --tuple-size option

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pgbench --tuple-size option
Date: 2014-08-16 12:23:37
Message-ID: alpine.DEB.2.10.1408152255110.29316@sto
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>>> The custom initialization is to run a manual ALTER after the
>>> initialization.
>>
>> Sure, it can be done this way.
>>
>> I'm not sure about the implication of ALTER on the table storage,
>
> Should be fine in this case.

After some testing and laughing, my conclusion is "not fine at all". The
"filler" attributes in "pgbench" are by default "EXTENDED", which mean
possibly compressed... As the the default value is '', the compression,
when tried for large sizes, performs very well, and the performance is the
same as with a (declared) smaller tuple:-) Probably not the intention of
the benchmark designer. Conclusion: I need an ALTER TABLE anyway to change
the STORAGE. Or maybe pgbench should always do it anyway...

Conclusion 2: I've noted the submission as "rejected" as both you and
Fujii don't like it, and although I found it useful, but I can do without
it quite easily.

--
Fabien.

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