Re: [Proposal] Global temporary tables - Mailing list pgsql-hackers
| From | Pavel Stehule |
|---|---|
| Subject | Re: [Proposal] Global temporary tables |
| Date | |
| Msg-id | CAFj8pRDTkjSWeyonnc8usDPJ4GybmqNV2R_1vb6hz4ZX9cjncw@mail.gmail.com Whole thread Raw |
| In response to | Re: [Proposal] Global temporary tables ("曾文旌(义从)" <wenjing.zwj@alibaba-inc.com>) |
| Responses |
Re: [Proposal] Global temporary tables
("曾文旌(义从)" <wenjing.zwj@alibaba-inc.com>)
Re: [Proposal] Global temporary tables ("曾文旌(义从)" <wenjing.zwj@alibaba-inc.com>) |
| List | pgsql-hackers |
Hi
so 11. 1. 2020 v 15:00 odesílatel 曾文旌(义从) <wenjing.zwj@alibaba-inc.com> napsal:
Hi allThis is the latest patchThe updates are as follows:1. Support global temp Inherit table global temp partition table2. Support serial column in GTT3. Provide views pg_gtt_relstats pg_gtt_stats for GTT’s statistics4. Provide view pg_gtt_attached_pids to manage GTT5. Provide function pg_list_gtt_relfrozenxids() to manage GTT6. Alter GTT or rename GTT is allowed under some conditionsPlease give me feedback.
I tested the functionality
1. i think so "ON COMMIT PRESERVE ROWS" should be default mode (like local temp tables).
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
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
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
Wenjing2020年1月6日 上午4:06，Tomas Vondra <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/
[2] 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
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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