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Re: Bad optimizer data for xml (WAS: xml data type implications of no =)

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Bad optimizer data for xml (WAS: xml data type implications of no =)
Date: 2010-06-09 03:22:46
Message-ID: AANLkTikXDv-OkulgAg8vegjMFiced3rgdHFUXSoNyKfD@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-bugs
On Thu, Jun 3, 2010 at 7:16 PM, Mark Kirkwood
<mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> wrote:
> Maybe I gave this guy a bad title - is it a concern that the 'width'
> estimate is so far off for xml datatypes (because of no = op)? It seemed to
> me that this could result in some bad plan choices (e.g in subqueries etc).

It's possible.  I don't really see a reason not to add an = operator
for XML - does anyone else?

It would need to be done by updating src/include/catalog/pg_*.h,
rather than via SQL, of course.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company

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