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: Pavel Stehule <pavel.stehule@gmail.com>
Cc: "Tomas Vondra" <tomas.vondra@2ndquadrant.com>, "Konstantin Knizhnik" <k.knizhnik@postgrespro.ru>, "Robert Haas" <robertmhaas@gmail.com>, "Julien Rouhaud" <rjuju123@gmail.com>, "Dean Rasheed" <dean.a.rasheed@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: 2020-01-21T08:45:53Z
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12日 上午4:27，Pavel Stehule <pavel.stehule@gmail.com> 写道：
> 
> Hi
> 
> so 11. 1. 2020 v 15:00 odesílatel 曾文旌(义从) <wenjing.zwj@alibaba-inc.com <mailto:wenjing.zwj@alibaba-inc.com>> napsal:
> Hi all
> 
> This is the latest patch
> 
> The updates are as follows:
> 1. Support global temp Inherit table global temp partition table
> 2. Support serial column in GTT
> 3. Provide views pg_gtt_relstats pg_gtt_stats for GTT’s statistics
> 4. Provide view pg_gtt_attached_pids to manage GTT
> 5. Provide function pg_list_gtt_relfrozenxids() to manage GTT
> 6. Alter GTT or rename GTT is allowed under some conditions
> 
> 
> Please give me feedback.
> 
> I tested the functionality
> 
> 1. i think so "ON COMMIT PRESERVE ROWS" should be default mode (like local temp tables).

ON COMMIT PRESERVE ROWS is default mode now.


Wenjing



> 
> I tested some simple scripts 
> 
> test01.sql
> 
> CREATE TEMP TABLE foo(a int, b int);
> INSERT INTO foo SELECT random()*100, random()*1000 FROM generate_series(1,1000);
> ANALYZE foo;
> SELECT sum(a), sum(b) FROM foo;
> DROP TABLE foo; -- simulate disconnect
> 
> 
> after 100 sec, the table pg_attribute has 3.2MB
> and 64 tps, 6446 transaction
> 
> test02.sql
> 
> INSERT INTO foo SELECT random()*100, random()*1000 FROM generate_series(1,1000);
> ANALYZE foo;
> SELECT sum(a), sum(b) FROM foo;
> DELETE FROM foo; -- simulate disconnect
> 
> 
> after 100 sec, 1688 tps, 168830 transactions
> 
> So performance is absolutely different as we expected.
> 
> From my perspective, this functionality is great.
> 
> Todo:
> 
> pg_table_size function doesn't work
> 
> Regards
> 
> Pavel
> 
> 
> Wenjing
> 
> 
> 
> 
> 
>> 2020年1月6日 上午4:06，Tomas Vondra <tomas.vondra@2ndquadrant.com <mailto:tomas.vondra@2ndquadrant.com>> 写道：
>> 
>> Hi,
>> 
>> I think we need to do something with having two patches aiming to add
>> global temporary tables:
>> 
>> [1] https://commitfest.postgresql.org/26/2349/ <https://commitfest.postgresql.org/26/2349/>
>> 
>> [2] https://commitfest.postgresql.org/26/2233/ <https://commitfest.postgresql.org/26/2233/>
>> 
>> As a reviewer I have no idea which of the threads to look at - certainly
>> not without reading both threads, which I doubt anyone will really do.
>> The reviews and discussions are somewhat intermixed between those two
>> threads, which makes it even more confusing.
>> 
>> I think we should agree on a minimal patch combining the necessary/good
>> bits from the various patches, and terminate one of the threads (i.e.
>> mark it as rejected or RWF). And we need to do that now, otherwise
>> there's about 0% chance of getting this into v13.
>> 
>> In general, I agree with the sentiment Rober expressed in [1] - the
>> patch needs to be as small as possible, not adding "nice to have"
>> features (like support for parallel queries - I very much doubt just
>> using shared instead of local buffers is enough to make it work.)
>> 
>> regards
>> 
>> -- 
>> Tomas Vondra                  http://www.2ndQuadrant.com <http://www.2ndquadrant.com/>
>> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>