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(义从) <wenjing.zwj@alibaba-inc.com>
Cc: 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>, 萧少聪(铁庵) <shaocong.xsc@alibaba-inc.com>
Date: 2020-02-15T10:06:18Z
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.

> postgres=# insert into foo select generate_series(1,10000);
> INSERT 0 10000
> postgres=# \dt+ foo
>                           List of relations
> ┌────────┬──────┬───────┬───────┬─────────────┬────────┬─────────────┐
> │ Schema │ Name │ Type  │ Owner │ Persistence │  Size  │ Description │
> ╞════════╪══════╪═══════╪═══════╪═════════════╪════════╪═════════════╡
> │ public │ foo  │ table │ pavel │ session     │ 384 kB │             │
> └────────┴──────┴───────┴───────┴─────────────┴────────┴─────────────┘
> (1 row)
>
> postgres=# truncate foo;
> TRUNCATE TABLE
> postgres=# \dt+ foo
>                           List of relations
> ┌────────┬──────┬───────┬───────┬─────────────┬───────┬─────────────┐
> │ Schema │ Name │ Type  │ Owner │ Persistence │ Size  │ Description │
> ╞════════╪══════╪═══════╪═══════╪═════════════╪═══════╪═════════════╡
> │ public │ foo  │ table │ pavel │ session     │ 16 kB │             │
> └────────┴──────┴───────┴───────┴─────────────┴───────┴─────────────┘
> (1 row)
>
> I expect zero size after truncate.
>
> Thanks for review.
>
> I can explain, I don't think it's a bug.
> The current implementation of the truncated GTT retains two blocks of FSM
> pages.
> The same is true for truncating regular tables in subtransactions.
> This is an implementation that truncates the table without changing the
> relfilenode of the table.
>
>
This is not extra important feature - now this is little bit a surprise,
because I was not under transaction.

Changing relfilenode, I think, is necessary, minimally for future VACUUM
FULL support.

Regards

Pavel Stehule


>
> Wenjing
>
>
> Regards
>
> Pavel
>
>
>>>
>>> Wenjing
>>>
>>>
>>>
>>>
>>> >
>>> > --
>>> > Robert Haas
>>> > EnterpriseDB: http://www.enterprisedb.com
>>> > The Enterprise PostgreSQL Company
>>>
>>>
>