Re: [Proposal] Global temporary tables

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)