Re: [Proposal] Global temporary tables

> 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
>>>
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