Re: Proposal: scan key push down to heap [WIP]

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal: scan key push down to heap [WIP]
Date: 2016-12-05 17:28:22
Message-ID: CA+TgmoZwD7fVfi1-86_mQbkgN7EiXK8FWbhGSWY1P-=93v96RQ@mail.gmail.com
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On Sat, Dec 3, 2016 at 10:30 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>> I'll post my new expression evaluation stuff - which doesn't do this
>> atm, but makes ExecQual faster in other ways - later this week. If we
>> could get the planner (or parse-analysis?) to set an OpExpr flag that
>> signals that the expression can be evaluated as a scankey, that'd be
>> easy.
>
> Isn't it better to directly make two separate lists during planning
> itself, one for regular qual and other which can be converted to
> scankey. Instead of keeping the flag in OpExpr ?

Well, I certainly think that in the end we need them in two separate
lists. But it's possible that a flag in the OpExpr could somehow be
useful in constructing those lists cheaply. I'm not sure I see what
Andres has in mind, though.

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

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