Re: [HACKERS] PoC plpgsql - possibility to force custom or generic plan
От | Pavel Stehule |
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Тема | Re: [HACKERS] PoC plpgsql - possibility to force custom or generic plan |
Дата | |
Msg-id | CAFj8pRDDtruyC10MOFUbA1FDsgQ1F+6XinDdZ9f3pY2GBr6rEw@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] PoC plpgsql - possibility to force custom or generic plan (Pavel Stehule <pavel.stehule@gmail.com>) |
Ответы |
Re: [HACKERS] PoC plpgsql - possibility to force custom or genericplan
|
Список | pgsql-hackers |
2017-04-06 12:30 GMT+02:00 Andrew Dunstan <andrew.dunstan@2ndquadrant.com>:
On 04/05/2017 05:41 PM, Andres Freund wrote:
> On 2017-04-05 17:22:34 -0400, Tom Lane wrote:
>> Andres Freund <andres@anarazel.de> writes:
>>> I'd like some input from other committers whether we want this. I'm
>>> somewhat doubtful, but don't have particularly strong feelings.
>> I don't really want to expose the workings of the plancache at user level.
>> The heuristics it uses certainly need work, but it'll get hard to change
>> those once there are SQL features depending on it.
>>
>> Also, as you note, there are debatable design decisions in this particular
>> patch. There are already a couple of ways in which control knobs can be
>> attached to plgsql functions (i.e. custom GUCs and the comp_option stuff),
>> so why is this patch wanting to invent yet another fundamental mechanism?
>> And I'm not very happy about it imposing a new reserved keyword, either.
>>
>> A bigger-picture question is why we'd only provide such functionality
>> in plpgsql, and not for other uses of prepared plans.
>>
>> Lastly, it doesn't look to me like the test cases prove anything at all
>> about whether the feature does what it's claimed to.
> That echoes my perception - so let's move this to the next CF? It's not
> like this patch has been pending for very long.
>
Or just Return with Feedback.
ISTM before we revisit this we need agreement on a design.
I am open to any ideas - there are some my start points
1. the possibility to disable plan cache is real request
2. can be useful if we are able to control plan cache inside function - the mix of settings is real case too
3. GUC are useless - nobody would to disable plan cache globally
I like to see any proposals about syntax or implementation.
Using PRAGMA is one variant - introduced by PLpgSQL origin - Ada language. The PRAGMA syntax can be used for PRAGMA autonomous with well known syntax. It scales well - it supports function, block or command level.
I invite any discussion now or in start of new release cycle.
Regards
Pavel
cheers
andrew
--
Andrew Dunstan https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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