Horton

Re: [Proposal] Global temporary tables

曾文旌 (义从) <wenjing.zwj@alibaba-inc.com>

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From: 曾文旌(义从) <wenjing.zwj@alibaba-inc.com>
To: Dean Rasheed <dean.a.rasheed@gmail.com>
Cc: "Tomas Vondra" <tomas.vondra@2ndquadrant.com>, "Konstantin Knizhnik" <k.knizhnik@postgrespro.ru>, "Pavel Stehule" <pavel.stehule@gmail.com>, "Robert Haas" <robertmhaas@gmail.com>, "PostgreSQL Hackers" <pgsql-hackers@postgresql.org>, 蔡松露(子嘉) <zijia@taobao.com>, Cai, Le <le.cai@alibaba-inc.com>, 萧少聪(铁庵) <shaocong.xsc@alibaba-inc.com>
Date: 2020-01-08T07:03:09Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. PageAddItemExtended(): Add LP_UNUSED assertion.

  2. Remove temporary files after backend crash

  3. Fix comment in indexing.c

  4. Fix failure to ignore leftover temp tables after a server crash.


> 2020年1月6日 下午8:17，Dean Rasheed <dean.a.rasheed@gmail.com> 写道：
> 
> On Mon, 6 Jan 2020 at 11:01, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
>> 
>> On Mon, Jan 06, 2020 at 01:04:15PM +0800, 曾文旌(义从) wrote:
>> 
>>> 2 We feel that gtt needs to maintain statistics, but there is no
>>> agreement on what it will be done.
>>> 
>> 
>> I certainly agree GTT needs to maintain statistics, otherwise it'll lead
>> to poor query plans.
> 
> +1
> 
>> AFAIK the current patch stores the info in a hash
>> table in a backend private memory, and I don't see how else to do that
>> (e.g. storing it in a catalog would cause catalog bloat).
>> 
> 
> It sounds like it needs a pair of system GTTs to hold the table and
> column statistics for other GTTs. One would probably have the same
> columns as pg_statistic, and the other just the relevant columns from
> pg_class. I can see it being useful for the user to be able to see
> these stats, so perhaps they could be UNIONed into the existing stats
> view.
The current patch provides several functions as extension(pg_gtt) for read gtt statistics. 
Next I can move them to the kernel and let the view pg_stats can see gtt’s statistics.


> Regards,
> Dean