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From: tushar <[email protected]>
To: 曾文旌(义从) <[email protected]>
To: Prabhat Sahu <[email protected]>
Cc: Pavel Stehule <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: Tomas Vondra <[email protected]>
Cc: Konstantin Knizhnik <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: 蔡松露(子嘉) <[email protected]>
Cc: Cai, Le <[email protected]>
Cc: 萧少聪(铁庵) <[email protected]>
Subject: Re: [Proposal] Global temporary tables
Date: Mon, 16 Mar 2020 14:28:17 +0530
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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	<[email protected]>
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	<[email protected]>

Hi Wenjing,

I have created a global table on X session but i am not able to drop 
from Y session ?

X session - ( connect to psql terminal )
postgres=# create global temp table foo(n int);
CREATE TABLE
postgres=# select * from foo;
  n
---
(0 rows)


Y session - ( connect to psql terminal )
postgres=# drop table foo;
ERROR:  can not drop relation foo when other backend attached this 
global temp table

Table has been created  so i think - user should be able to drop from 
another session as well without exit from X session.

regards,

On 3/16/20 1:35 PM, 曾文旌(义从) wrote:
>
>
>> 2020年3月16日 下午2:23，Prabhat Sahu <[email protected] 
>> <mailto:[email protected]>> 写道：
>>
>> 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)
>>
>> -- 
>
> I understand that postgre_fdw works similar to dblink.
> postgre_fdw access to the table requires a new connection.
> The data in the GTT table is empty in the newly established connection.
> Because GTT shares structure but not data between connections.
>
> Try local temp table:
> create temporary table ltt1 (c1 integer, c2 varchar(50));
>
> insert into ltt1 values (1,'gtt_c21');
>
> create foreign table f_ltt1 (c1 integer, c2 varchar(50)) server fdw 
> options (table_name 'ltt1');
>
> select * from ltt1;
>  c1 |   c2
> ----+---------
>   1 | gtt_c21
> (1 row)
>
> select * from l_gtt1;
> ERROR:  relation "l_gtt1" does not exist
> LINE 1: select * from l_gtt1;
>
>
> Wenjing
>
>
>> With Regards,
>> Prabhat Kumar Sahu
>> EnterpriseDB: http://www.enterprisedb.com <http://www.enterprisedb.com/;
>>
>

-- 
regards,tushar
EnterpriseDB  https://www.enterprisedb.com/
The Enterprise PostgreSQL Company

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