Horton

Re: [Proposal] Global temporary tables

Konstantin Knizhnik <k.knizhnik@postgrespro.ru>

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From: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
To: Prabhat Sahu <prabhat.sahu@enterprisedb.com>, 曾文旌(义从) <wenjing.zwj@alibaba-inc.com>
Cc: tushar <tushar.ahuja@enterprisedb.com>, Pavel Stehule <pavel.stehule@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, 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: 2020-03-16T07:59:40Z
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.


On 16.03.2020 9:23, Prabhat Sahu wrote:
> Hi Wenjing,
> Please check the below scenario, where the Foreign table on GTT not 
> showing records.
>
> postgres=# create extension postgres_fdw;
> CREATE EXTENSION
> postgres=# do $d$
>     begin
>         execute $$create server fdw foreign data wrapper postgres_fdw 
> options (host 'localhost',dbname 'postgres',port 
> '$$||current_setting('port')||$$')$$;
>     end;
> $d$;
> DO
> postgres=# create user mapping for public server fdw;
> CREATE USER MAPPING
>
> postgres=# create table lt1 (c1 integer, c2 varchar(50));
> CREATE TABLE
> postgres=# insert into lt1 values (1,'c21');
> INSERT 0 1
> postgres=# create foreign table ft1 (c1 integer, c2 varchar(50)) 
> server fdw options (table_name 'lt1');
> CREATE FOREIGN TABLE
> postgres=# select * from ft1;
>  c1 | c2
> ----+-----
>   1 | c21
> (1 row)
>
> postgres=# create global temporary table gtt1 (c1 integer, c2 
> varchar(50));
> CREATE TABLE
> postgres=# insert into gtt1 values (1,'gtt_c21');
> INSERT 0 1
> postgres=# create foreign table f_gtt1 (c1 integer, c2 varchar(50)) 
> server fdw options (table_name 'gtt1');
> CREATE FOREIGN TABLE
>
> postgres=# select * from gtt1;
>  c1 |   c2
> ----+---------
>   1 | gtt_c21
> (1 row)
>
> postgres=# select * from f_gtt1;
>  c1 | c2
> ----+----
> (0 rows)
>
> -- 
>
> With Regards,
> Prabhat Kumar Sahu
> EnterpriseDB: http://www.enterprisedb.com <http://www.enterprisedb.com/>
>

It seems to be expected behavior: GTT data is private to the session and 
postgres_fdw establish its own session where content of the table is empty.
But if you insert some data in f_gtt1, then you will be able to select 
this data from it because of connection cache in postgres_fdw.

-- 

Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company