Re: CTE materializing sets? - Mailing list pgsql-general

From Serge Fonville
Subject Re: CTE materializing sets?
Date
Msg-id CAOAS_+K0cWDma4+51gdyJVBAE9Jc-8C=POgV1-_o09_x4OKEZQ@mail.gmail.com
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In response to Re: CTE materializing sets?  (Craig Ringer <ringerc@ringerc.id.au>)
Responses Re: CTE materializing sets?  (Craig Ringer <ringerc@ringerc.id.au>)
Re: CTE materializing sets?  (Виктор Егоров <vyegorov@gmail.com>)
List pgsql-general
This indeed is a very interesting question.

At http://wiki.postgresql.org/wiki/CTEReadme it seems to suggest that a CTE is just rewritten and the resulting query is executed.

Kind regards/met vriendelijke groet,

Serge Fonville

http://www.sergefonville.nl

Convince Microsoft!
They need to add TRUNCATE PARTITION in SQL Server



2012/10/9 Craig Ringer <ringerc@ringerc.id.au>
On 10/06/2012 08:45 AM, Liam Caffrey wrote:
Hi,

If I run a CTE does that materialize the resulting data in the same (or
a similar) way as if I created a temp table and referred to that
instead? Or does the CTE keep the set in memory?

Really good question, I too would be interested in this.

I'd expect it'd materialize to RAM if the result is within `work_mem` but I'd love to know for sure.

--
Craig Ringer



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