Re: [PATCHES] libpq type system 0.9a

From: Andrew Chernow <ac(at)esilo(dot)com>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: Andrew Dunstan <andrew(at)dunslane(dot)net>, Gregory Stark <stark(at)enterprisedb(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Joe Conway <mail(at)joeconway(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [PATCHES] libpq type system 0.9a
Date: 2008-04-09 12:35:11
Message-ID: 47FCB7FF.3000204@esilo.com
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Merlin Moncure wrote:
> On Wed, Apr 9, 2008 at 8:04 AM, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
> \> Merlin Moncure wrote:
>>> However, due to libpq limitations, if any datatype must
>>> return text the entire result must be text (resultFormat)...this is
>>> also interestingly true for functions that return 'void'. So, at
>>> present, to use PQgetf, you result set must be binary.
>> I'm surprised you didn't try to address that limitation.
>
>
> whoops! we did...thinko on my part. Text results are fully supported
> save for composites and arrays.
>
> merlin
>

Yeah, currently composites and arrays only support binary results in libpqtypes.
This forces any array elementType or any member of a composite to have a
send/recv routine. Using the "fallback to text output" approach, this
limitation on array elements and composite members would be removed.

>>That makes it sound more like a protocol limitation, rather than a
>>libpq limitation. Or am I misunderstanding?
It looks like libpq, message 'T' handling in getRowDescriptions, reads a
separate format for each column off the wire. The protocol already has this
ability. The backend needs a ?minor? adjustment to make use of the existing
capability.

--
Andrew Chernow
eSilo, LLC
every bit counts
http://www.esilo.com/

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