From: Tom Lane <tgl@sss.pgh.pa.us>
To: Craig James <cjames@emolecules.com>
cc: Atri Sharma <atri.jiit@gmail.com>, Stefan Keller <sfkeller@gmail.com>,
 "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Getting query plan alternatives from query planner?
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Comments: In-reply-to Craig James <cjames@emolecules.com>
 message dated "Fri, 21 Mar 2014 06:34:55 -0700"
Date: Fri, 21 Mar 2014 10:06:51 -0400
Message-ID: <15381.1395410811@sss.pgh.pa.us>
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Craig James <cjames@emolecules.com> writes:
> There have been many discussions about adding hints to Postgres over the
> years. All have been firmly rejected by the Postgres developers, with
> well-argued reasons.  Search the archives to learn more about this topic.

To clarify: there are good reasons not to like what Oracle calls hints.
On the other hand, the concept of hints that tell the planner what
selectivity or rowcount to expect (as opposed to trying to control the
plan directly) has met with generally more positive reviews.  There's
no specific design yet, and certainly no implementation roadmap, but
I'd not be surprised if we get something like that a few years down
the road.

			regards, tom lane


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