数据仓库服务 GAUSSDB(DWS)-DISCARD:示例

时间：2024-06-29 17:51:35

示例

DISCARD VOLATILE临时表

DISCARD操作后，清理当前会话中所有volatile临时表相关资源。

    
         CREATE VOLATILE TEMP TABLE TX1(A INT) DISTRIBUTE BY HASH(A);
CREATE TABLE
CREATE VOLATILE TEMP TABLE TX2(A INT) DISTRIBUTE BY HASH(A);
CREATE TABLE

SELECT * FROM TX1;
 a
---
(0 rows)
SELECT * FROM TX2;
 a
---
(0 rows)

DISCARD VOLATILE TEMP;

SELECT * FROM TX1;
ERROR:  relation "tx1" does not exist
LINE 1: SELECT * FROM TX1;
                      ^
SELECT * FROM TX2;
ERROR:  relation "tx2" does not exist
LINE 1: SELECT * FROM TX2;

DISCARD TEMP

DISCARD TEMP操作后，清理当前会话中所有临时表相关资源。

     
          CREATE GLOBAL TEMP TABLE t_global_temp(a int,b int);
NOTICE:  The 'DISTRIBUTE BY' clause is not specified. Using round-robin as the distribution mode by default.
HINT:  Please use 'DISTRIBUTE BY' clause to specify suitable data distribution column.
CREATE TABLE
INSERT INTO t_global_temp VALUES(1,1),(2,2);
INSERT 0 2

CREATE VOLATILE TEMP TABLE t_volatile_temp(a int,b int);
CREATE TEMP TABLE t_temp(a int,b int);

DISCARD TEMP;

SELECT * FROM t_global_temp;
 a | b
---+---
(0 rows)

SELECT * FROM t_volatile_temp;
ERROR:  relation "t_volatile_temp" does not exist
LINE 1: select * from t_volatile_temp;

SELECT * FROM t_temp;
ERROR:  relation "t_temp" does not exist
LINE 1: select * from t_temp;