| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Atri Sharma <atri(dot)jiit(at)gmail(dot)com> |
| Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Mart Kelder <mart(at)kelder31(dot)nl>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Subject: | Re: Removing INNER JOINs |
| Date: | 2014-12-03 18:17:09 |
| Message-ID: | 20761.1417630629@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Atri Sharma <atri(dot)jiit(at)gmail(dot)com> writes:
> On Wed, Dec 3, 2014 at 11:38 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I think the right approach for now is to emulate the GEQO precedent as
>> closely as possible. Build all the single-relation Paths the same as
>> now, then do a join search over all the relations, then (if we've noticed
>> that some joins are potentially removable) do another join search over
>> just the nonremovable relations.
> How about using geqo more liberally when replanning (decrease the number of
> relations in join before geqo is hit?)
This is going to be quite difficult enough without overcomplicating it.
Or as a wise man once said, "premature optimization is the root of all
evil". Get it working in the basic way and then see if improvement is
necessary at all.
regards, tom lane
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