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UPDATE using sub selects

From: NikhilS <nikkhils(at)gmail(dot)com>
To: pgsql-patches(at)postgresql(dot)org
Subject: UPDATE using sub selects
Date: 2007-04-11 08:26:22
Message-ID: d3c4af540704110126o5b6c9c79na40ae4d4c6236d06@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-patches
Hi,

As per discussion on -hackers, a patch which allows updates to use
subselects is attached with this mail.

As per discussion with Tom, I have adopted the following approach:

* Introduce ROWEXPR_SUBLINK type for subqueries that allows multiple column
outputs.
* Populate the targetList with PARAM_SUBLINK entries dependent on the
subselects.
* Modify the targets in-place into PARAM_EXEC entries in the make_subplan
phase.

The above does not require any kluges in the targetList processing code path
at all.

UPDATEs seem to work fine using subselects with this patch. I have modified
the update.sql regression test to include possible variations .

No documentation changes are present in this patch.
Feedback, comments appreciated.

Regards,
Nikhils
-- 
EnterpriseDB               http://www.enterprisedb.com

Attachment: updates_using_subselects.patch
Description: text/x-patch (37.2 KB)

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