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Re: [Proposal] Global temporary tables

Prabhat Sahu <prabhat.sahu@enterprisedb.com>

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From: Prabhat Sahu <prabhat.sahu@enterprisedb.com>
To: 曾文旌(义从) <wenjing.zwj@alibaba-inc.com>
Cc: Pavel Stehule <pavel.stehule@gmail.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>, 萧少聪(铁庵) <shaocong.xsc@alibaba-inc.com>
Date: 2020-02-25T13:36:07Z
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 All,

Please check the below findings on GTT.
*-- Scenario 1:*
Under "information_schema", We are not allowed to create "temporary table",
whereas we can CREATE/DROP "Global Temporary Table", is it expected ?

postgres=# create temporary table information_schema.temp1(c1 int);
ERROR:  cannot create temporary relation in non-temporary schema
LINE 1: create temporary table information_schema.temp1(c1 int);
                               ^

postgres=# create global temporary table information_schema.temp1(c1 int);
CREATE TABLE

postgres=# drop table information_schema.temp1 ;
DROP TABLE

*-- Scenario 2:*
Here I am getting the same error message in both the below cases.
We may add a "global" keyword with GTT related error message.

postgres=# create global temporary table gtt1 (c1 int unique);
CREATE TABLE
postgres=# create temporary table tmp1 (c1 int unique);
CREATE TABLE

postgres=# create temporary table tmp2 (c1 int references gtt1(c1) );
ERROR:  constraints on temporary tables may reference only temporary tables

postgres=# create global temporary table gtt2 (c1 int references tmp1(c1) );
ERROR:  constraints on temporary tables may reference only temporary tables

Thanks,
Prabhat Sahu

On Tue, Feb 25, 2020 at 2:25 PM 曾文旌(义从) <wenjing.zwj@alibaba-inc.com> wrote:

>
>
> 2020年2月24日 下午5:44，Prabhat Sahu <prabhat.sahu@enterprisedb.com> 写道：
>
> On Fri, Feb 21, 2020 at 9:10 PM 曾文旌(义从) <wenjing.zwj@alibaba-inc.com>
> wrote:
>
>> Hi,
>> I have started testing the "Global temporary table" feature,
>> That's great, I see hope.
>> from "gtt_v11-pg13.patch". Below is my findings:
>>
>> -- session 1:
>> postgres=# create global temporary table gtt1(a int);
>> CREATE TABLE
>>
>> -- seeeion 2:
>> postgres=# truncate gtt1 ;
>> ERROR:  could not open file "base/13585/t3_16384": No such file or
>> directory
>>
>> is it expected?
>>
>> Oh ,this is a bug, I fixed it.
>>
> Thanks for the patch.
> I have verified the same, Now the issue is resolved with v12 patch.
>
> Kindly confirm the below scenario:
>
> postgres=# create global temporary table gtt1 (c1 int unique);
> CREATE TABLE
>
> postgres=# create global temporary table gtt2 (c1 int references gtt1(c1)
> );
> ERROR:  referenced relation "gtt1" is not a global temp table
>
> postgres=# create table tab2 (c1 int references gtt1(c1) );
> ERROR:  referenced relation "gtt1" is not a global temp table
>
> Thanks,
> Prabhat Sahu
>
>
> GTT supports foreign key constraints
> in global_temporary_table_v13-pg13.patch
>
>
> Wenjing
>
>
>
>

-- 

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