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From: Merlin Moncure <mmoncure@gmail.com>
To: Grzegorz Jaśkiewicz <gryzman@gmail.com>
Cc: Eliot Gable <egable+pgsql-performance@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Replacing Cursors with Temporary Tables
Date: Sat, 24 Apr 2010 11:20:12 -0400
Message-ID: <y2kb42b73151004240820u5a0082dt2201eef3c4dafa87@mail.gmail.com> (raw)
In-Reply-To: <p2k2f4958ff1004240738i91f8b5eco8b4571f994e15254@mail.gmail.com>
References: <n2ybf6923ed1004211316ib844d82bn7a63bd3292ca80a0@mail.gmail.com>
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	<m2gbf6923ed1004221357ua9ab54a3s92dfdbb59cfef832@mail.gmail.com>
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	<s2lb42b73151004240623h78726052h4f30fade77f8b572@mail.gmail.com>
	<p2k2f4958ff1004240738i91f8b5eco8b4571f994e15254@mail.gmail.com>

2010/4/24 Grzegorz Jaśkiewicz <gryzman@gmail.com>:
>
>
> On Sat, Apr 24, 2010 at 2:23 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
>>
>> Well, you missed the most important part: not using cursors at all.
>> Instead of declaring a cursor and looping it to build the array, build
>> it with array().  That's what I've been saying: arrays can completely
>> displace both temp tables _and_ cursors when passing small sets around
>> functions.
>>
> with huge emphasis on the word small.

The rule of thumb I use is 10000 narrow records (scalars, or very
small composites) or 1000 wide/complex records.  I routinely pass
extremely complex (3-4 levels nesting) nested composite arrays to the
client for processing -- it is extremely efficient and clean.  This of
course is going to depend on hardware and other factors.

merlin



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