Re: Pushdown target list below gather node (WAS Re: WIP: Upper planner pathification) - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Pushdown target list below gather node (WAS Re: WIP: Upper planner pathification)
Date
Msg-id CA+TgmoZ0vmTZxBHruZ0ywypoRguap4Um2a7UdeH=QpjTzWCGag@mail.gmail.com
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In response to Re: Pushdown target list below gather node (WAS Re: WIP: Upper planner pathification)  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Fri, Mar 18, 2016 at 10:08 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> OK, I've committed something along those lines.  Thanks for the
>> advice, and feel free to whack it around if you have an idea for
>> improving it further - though IMHO this is good enough for 9.6.
>
> The committed patch looks fine to me.  WRT your commit-message comment
> about pushing down only parallel-safe tlist expressions, I would strongly
> advise leaving that for another day.  I have some irons in the fire
> concerning ways to push down computation of index expressions (so that
> we can consistently get f(x) out of an index on f(x) rather than
> recomputing it), and managing parallel-safe expressions seems like it'd
> benefit from that infrastucture too.

Roger.

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



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