Re: [Proposal] Global temporary tables
| От | Pavel Stehule |
|---|---|
| Тема | Re: [Proposal] Global temporary tables |
| Дата | |
| Msg-id | CAFj8pRBNssuJoYH6d51-yqOfV2_nB+aK-Mj7maLPQH+O8cm-TA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [Proposal] Global temporary tables (Pavel Stehule <pavel.stehule@gmail.com>) |
| Ответы |
Re: [Proposal] Global temporary tables
("曾文旌(义从)" <wenjing.zwj@alibaba-inc.com>)
|
| Список | pgsql-hackers |
čt 30. 1. 2020 v 15:21 odesílatel Pavel Stehule <pavel.stehule@gmail.com> napsal:
čt 30. 1. 2020 v 15:17 odesílatel 曾文旌(义从) <wenjing.zwj@alibaba-inc.com> napsal:
> 2020年1月29日 下午9:48，Robert Haas <robertmhaas@gmail.com> 写道：
>
> On Tue, Jan 28, 2020 at 12:12 PM 曾文旌(义从) <wenjing.zwj@alibaba-inc.com> wrote:
>>> Opinion by Pavel
>>> + rel->rd_islocaltemp = true; <<<<<<< if this is valid, then the name of field "rd_islocaltemp" is not probably best
>>> I renamed rd_islocaltemp
>>
>> I don't see any change?
>>
>> Rename rd_islocaltemp to rd_istemp in global_temporary_table_v8-pg13.patch
>
> In view of commit 6919b7e3294702adc39effd16634b2715d04f012, I think
> that this has approximately a 0% chance of being acceptable. If you're
> setting a field in a way that is inconsistent with the current use of
> the field, you're probably doing it wrong, because the field has an
> existing purpose to which new code must conform. And if you're not
> doing that, then you don't need to rename it.
Thank you for pointing it out.
I've rolled back the rename.
But I still need rd_localtemp to be true, The reason is that
1 GTT The GTT needs to support DML in read-only transactions ,like local temp table.
2 GTT does not need to hold the lock before modifying the index buffer ,also like local temp table.
Please give me feedback.maybe some likerel->rd_globaltemp = true;and somewhere elseif (rel->rd_localtemp || rel->rd_globaltemp){...}
I tested this patch again and I am very well satisfied with behave.
what doesn't work still - TRUNCATE statement
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)
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.
Regards
Pavel
Wenjing
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
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