Re: [Proposal] Global temporary tables

2020年3月12日 下午8:22，Prabhat Sahu <prabhat.sahu@enterprisedb.com> 写道：

Hi Wenjing,

Please check the below findings:
After running "TRUNCATE" command, the "relfilenode" field is not changing for GTT 

whereas, for Simple table/Temp table "relfilenode" field is changing after TRUNCATE.

Case 1: Getting same "relfilenode" for GTT after and before "TRUNCATE"
postgres=# create global temporary table gtt1(c1 int) on commit delete rows;
CREATE TABLE
postgres=# select relfilenode from pg_class  where relname ='gtt1';
 relfilenode
-------------
       16384
(1 row)
postgres=# truncate gtt1;
TRUNCATE TABLE
postgres=# select relfilenode from pg_class  where relname ='gtt1';
 relfilenode
-------------
       16384
(1 row)

postgres=# create global temporary table gtt2(c1 int) on commit preserve rows;
CREATE TABLE
postgres=# select relfilenode from pg_class  where relname ='gtt2';
 relfilenode
-------------
       16387
(1 row)

postgres=# truncate gtt2;
TRUNCATE TABLE
postgres=# select relfilenode from pg_class  where relname ='gtt2';

 relfilenode
-------------
       16387
(1 row)


Case 2: "relfilenode" changes after "TRUNCATE" for Simple table/Temp table
postgres=# create temporary table temp3(c1 int) on commit preserve rows;
CREATE TABLE
postgres=# select relfilenode from pg_class  where relname ='temp3';
 relfilenode
-------------
       16392
(1 row)
postgres=# truncate temp3;
TRUNCATE TABLE
postgres=# select relfilenode from pg_class  where relname ='temp3';
 relfilenode
-------------
       16395
(1 row)


postgres=# create table tabl4(c1 int);
CREATE TABLE
postgres=# select relfilenode from pg_class  where relname ='tabl4';
 relfilenode
-------------
       16396
(1 row)
postgres=# truncate tabl4;
TRUNCATE TABLE
postgres=# select relfilenode from pg_class  where relname ='tabl4';
 relfilenode
-------------
       16399
(1 row)

On Thu, Mar 12, 2020 at 3:36 PM 曾文旌(义从) <wenjing.zwj@alibaba-inc.com> wrote:

> 2020年3月12日 上午4:12，Robert Haas <robertmhaas@gmail.com> 写道：
>
> On Wed, Mar 11, 2020 at 9:07 AM 曾文旌(义从) <wenjing.zwj@alibaba-inc.com> wrote:
>> reindex need change relfilenode, but GTT is not currently supported.
>
> In my view that'd have to be fixed somehow.
Ok , I am working on it.



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

--

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