| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Amit Langote <amitlangote09(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, amul sul <sulamul(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
| Subject: | Re: [HACKERS] Runtime Partition Pruning |
| Date: | 2018-04-18 15:13:01 |
| Message-ID: | CA+TgmoaEofE85BbLycU5XB9sDvaXdWFOX3oO=XW4fKfx6kAR9g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Apr 16, 2018 at 10:46 PM, David Rowley
<david(dot)rowley(at)2ndquadrant(dot)com> wrote:
> I did go and start working on a patch to test how possible this would
> be and came up with the attached. I've left a stray
> MemoryContextStatsDetail call in there which does indicate that
> something is not being freed. I'm just not sure what it is yet.
>
> The patch does happen to improve performance slightly, but that is
> most likely due to the caching of the ExprStates rather than the
> change of memory management. It's not really possible to do that with
> the reset unless we stored the executor's memory context in
> PartitionPruneContext and did a context switch back inside
> partkey_datum_from_expr before calling ExecInitExpr.
10% is more than a "slight" improvement, I'd say! It's certainly got
to be worth avoiding the repeated calls to ExecInitExpr, whatever we
do about the memory contexts.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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