Horton

Re: [Proposal] Global temporary tables

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: 曾文旌 <wenjing.zwj@alibaba-inc.com>
Cc: Prabhat Sahu <prabhat.sahu@enterprisedb.com>, tushar <tushar.ahuja@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Konstantin Knizhnik <k.knizhnik@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, 蔡松露(子嘉) <zijia@taobao.com>, "Cai, Le" <le.cai@alibaba-inc.com>
Date: 2020-07-07T10:05:42Z
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.

Hi


> GTT Merge the latest PGMaster and resolves conflicts.
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>
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I tested it and it looks fine. I think it is very usable in current form,
but still there are some issues:

postgres=# create global temp table foo(a int);
CREATE TABLE
postgres=# insert into foo values(10);
INSERT 0 1
postgres=# alter table foo add column x int;
ALTER TABLE
postgres=# analyze foo;
WARNING:  reloid 16400 not support update attstat after add colunm
WARNING:  reloid 16400 not support update attstat after add colunm
ANALYZE

Please, can you summarize what is done, what limits are there, what can be
implemented hard, what can be implemented easily?



I found one open question - how can be implemented table locks - because
data is physically separated, then we don't need table locks as protection
against race conditions.

Now, table locks are implemented on a global level. So exclusive lock on
GTT in one session block insertion on the second session. Is it expected
behaviour? It is safe, but maybe it is too strict.

We should define what table lock is meaning on GTT.

Regards

Pavel


> Pavel
>
>
>> With Regards,
>> Prabhat Kumar Sahu
>> EnterpriseDB: http://www.enterprisedb.com
>>
>>
>>
>