public inbox for [email protected]  

help / color / mirror / Atom feed

From: Tomas Vondra <[email protected]>
To: Julien Rouhaud <[email protected]>
Cc: Konstantin Knizhnik <[email protected]>
Cc: 曾文旌(义从) <[email protected]>
Cc: Pavel Stehule <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: 蔡松露(子嘉) <[email protected]>
Cc: Cai, Le <[email protected]>
Cc: 萧少聪(铁庵) <[email protected]>
Subject: Re: [Proposal] Global temporary tables
Date: Mon, 13 Jan 2020 22:03:01 +0100
Message-ID: <20200113210301.yakqxdmxjh2ogq6x@development> (raw)
In-Reply-To: <20200113201216.GA17684@nol>
References: <[email protected]>
	<20200105200603.wrb4beacwb57hhpk@development>
	<[email protected]>
	<[email protected]>
	<20200109164829.mdl3z5xalmaqxs67@development>
	<[email protected]>
	<20200112015109.caab6qdr2ob6d5jv@development>
	<[email protected]>
	<20200113163253.ja34iqsors3o44sv@development>
	<20200113201216.GA17684@nol>

On Mon, Jan 13, 2020 at 09:12:38PM +0100, Julien Rouhaud wrote:
>On Mon, Jan 13, 2020 at 05:32:53PM +0100, Tomas Vondra wrote:
>> On Mon, Jan 13, 2020 at 11:08:40AM +0300, Konstantin Knizhnik wrote:
>> >
>> >"if any code tried to access the statistics directly from the table,
>> >rather than via the caches".
>> >
>> >Currently optimizer is accessing statistic though caches. So this
>> >approach works. If somebody will rewrite optimizer or provide own
>> >custom optimizer in extension which access statistic directly
>> >then it we really be a problem. But I wonder why bypassing catalog
>> >cache may be needed.
>> >
>>
>> I don't know, but it seems extensions like hypopg do it.
>
>AFAIR, hypopg only opens pg_statistic to use its tupledesc when creating
>statistics on hypothetical partitions, but it should otherwise never reads or
>need plain pg_statistic rows.

Ah, OK! Thanks for the clarification. I knew it does something with the
catalog, didn't realize it only gets the descriptor.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services 

view thread (492+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
  Subject: Re: [Proposal] Global temporary tables
  In-Reply-To: <20200113210301.yakqxdmxjh2ogq6x@development>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox