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Re: Optimize postgres protocol for fixed size arrays

From: "ktm(at)rice(dot)edu" <ktm(at)rice(dot)edu>
To: Mikko Tiihonen <mikko(dot)tiihonen(at)nitorcreations(dot)com>
Cc: pgsql-jdbc(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Optimize postgres protocol for fixed size arrays
Date: 2011-11-22 21:58:06
Message-ID: (view raw or whole thread)
Lists: pgsql-hackerspgsql-jdbc
On Tue, Nov 22, 2011 at 11:47:22PM +0200, Mikko Tiihonen wrote:
> Hi,
> During conversion of the jdbc driver to use binary encoding when receiving array objects from postgres it was noticed
> that for example for int[] arrays the binary encoding is normally 30% to 200% larger in bytes than the text encoding.
> This was of concern to some users with slower links to database. Even though the encoded size was larger the binary
> encoding was still constantly faster (with 50% speed up for float[]).
> Here is a patch that adds a new flag to the protocol that is set when all elements of the array are of same fixed size.
> When the bit is set the 4 byte length is only sent once and not for each element. Another restriction is that the flag
> can only be set when there are no NULLs in the array.

Cool. This would be very useful with the DSPAM binary array driver. Although
the binary is shorter because the values are 8 byte integers, they would be
much shorter without the redundant sizing information. Barring issues:



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