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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <david.rowley@2ndquadrant.com>
cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>,
        Dmitry Dolgov <9erthalion6@gmail.com>,
        Jeff Janes <jeff.janes@gmail.com>,
        Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>,
        Pavel Stehule <pavel.stehule@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: why partition pruning doesn't work?
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Comments: In-reply-to David Rowley <david.rowley@2ndquadrant.com>
	message dated "Wed, 06 Jun 2018 21:52:04 +1200"
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Date: Thu, 07 Jun 2018 11:43:12 -0400
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David Rowley <david.rowley@2ndquadrant.com> writes:
> On 6 June 2018 at 18:05, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote:
>> I wonder why we need to create those Bitmapsets in the planner?  Why not
>> in ExecSetupPartitionPruneState()?  For example, like how
>> context->exprstates is initialized.

> That seems like a good idea.  Certainly much better than working them
> out each time we prune.

> v3 patch attached.

Maybe there's something I'm missing here, but I sort of hoped that this
patch would nuke all the special-case code for Params in this area.
Why is there any need to distinguish them from other stable expressions?

IOW, I was hoping for the code to end up simpler, not more complicated.

			regards, tom lane