Re: 9.3 Pre-proposal: Range Merge Join - Mailing list pgsql-hackers

From Robert Haas
Subject Re: 9.3 Pre-proposal: Range Merge Join
Date
Msg-id BE156338-2EE4-4830-9C97-B685AB6CAFB4@gmail.com
Whole thread Raw
In response to 9.3 Pre-proposal: Range Merge Join  (Jeff Davis <pgsql@j-davis.com>)
Responses Re: 9.3 Pre-proposal: Range Merge Join  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Apr 16, 2012, at 1:40 AM, Jeff Davis <pgsql@j-davis.com> wrote:
> See attached SQL for example. The
> Problem statement: slow. Nested loops are the only option, although they
> can benefit from an inner GiST index if available. But if the join is
> happening up in the plan tree somewhere, then it's impossible for any
> index to be available.

Hmm. This sounds like something that Tom's recent work on parameterized plans ought to have fixed, or if not, it seems
closelyrelated. And by "this" I mean specifically the ability to use a GiST index to drive a nested loop that is higher
upin the plan tree than the immediate parent of the index scan. 

This is not an argument against your proposal, just an observation.

...Robert

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