Trafodion中每个对象(如表、索引等)创建后,会在元数据表中增加相应的记录,主要元数据表为"_MD_".objects。
以下是"_MD_".objects的表结构,
SQL>showddl "_MD_".objects;
CREATE TABLE TRAFODION."_MD_".OBJECTS
(
CATALOG_NAME VARCHAR(256 BYTES) CHARACTER SET UTF8
COLLATE DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, SCHEMA_NAME VARCHAR(256 BYTES) CHARACTER SET UTF8
COLLATE DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, OBJECT_NAME VARCHAR(256 BYTES) CHARACTER SET UTF8
COLLATE DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, OBJECT_TYPE CHAR(2) CHARACTER SET ISO88591 COLLATE
DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, OBJECT_UID LARGEINT NO DEFAULT NOT NULL NOT DROPPABLE
NOT SERIALIZED
, CREATE_TIME LARGEINT NO DEFAULT NOT NULL NOT DROPPABLE
NOT SERIALIZED
, REDEF_TIME LARGEINT NO DEFAULT NOT NULL NOT DROPPABLE
NOT SERIALIZED
, VALID_DEF CHAR(2) CHARACTER SET ISO88591 COLLATE
DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, DROPPABLE CHAR(2) CHARACTER SET ISO88591 COLLATE
DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, OBJECT_OWNER INT NO DEFAULT NOT NULL NOT DROPPABLE NOT
SERIALIZED
, SCHEMA_OWNER INT NO DEFAULT NOT NULL NOT DROPPABLE NOT
SERIALIZED
, FLAGS LARGEINT NO DEFAULT NOT NULL NOT DROPPABLE
NOT SERIALIZED
, CONSTRAINT TRAFODION."_MD_".OBJECTS_PK PRIMARY KEY (CATALOG_NAME ASC,
SCHEMA_NAME ASC, OBJECT_NAME ASC, OBJECT_TYPE ASC)
)
ATTRIBUTES NAMESPACE 'TRAF_RSRVD_1'
;
CREATE UNIQUE INDEX OBJECTS_UNIQ_IDX ON TRAFODION."_MD_".OBJECTS
(
OBJECT_UID ASC
)
;
“_MD_”.objects中有两个字段CREATE_TIME及REDEF_TIME,分别表示创建时间和更新时间,它们的类型为largeint,需要使用CONVERTTIMESTAMP转换为时间戳,另外,转换后的时间戳为UETC时间,需要+8小时转换为CST时间。
因此,想查看一个表的创建时间和修改时间的方法如下,
SELECT converttimestamp(create_time)+interval '8' HOUR AS create_time ,
converttimestamp(redef_time)+interval '8' HOUR AS redef_time
FROM "_MD_".objects AS a WHERE a.object_name=<object_name>;
如,
SQL>SELECT converttimestamp(create_time)+interval '8' HOUR AS create_time ,
+> converttimestamp(redef_time)+interval '8' HOUR AS redef_time
+>FROM "_MD_".objects AS a WHERE a.object_name='T_BUET_BUSINESSEVENT';
CREATE_TIME REDEF_TIME
-------------------------- --------------------------
2019-07-17 18:31:54.752077 2019-08-21 11:51:17.935288
--- 1 row(s) selected.