Re: [Proposal] Global temporary tables - Mailing list pgsql-hackers

From Pavel Stehule
Subject Re: [Proposal] Global temporary tables
Date
Msg-id CAFj8pRBSFwhj+iccFF50WdrruAXbMsvqTMTfCVu9x2LPcvnd2w@mail.gmail.com
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In response to Re: [Proposal] Global temporary tables  ("曾文旌(义从)" <wenjing.zwj@alibaba-inc.com>)
Responses Re: [Proposal] Global temporary tables
Re: [Proposal] Global temporary tables
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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 like

rel->rd_globaltemp = true;

and somewhere else

if (rel->rd_localtemp || rel->rd_globaltemp)
{
  ...
}



Wenjing




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

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