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DESCRIBE 语句
DESCRIBE 语句 #
DESCRIBE 语句用于描述表或视图的 schema，或catalog 的元数据，或 Flink 集群上的指定作业。
执行 DESCRIBE 语句 #
可以使用 TableEnvironment 的 executeSql() 方法执行 DESCRIBE 语句。如果 DESCRIBE 操作执行成功，executeSql() 方法会返回所有对象，否则会抛出异常。
以下示例展示了如何在 TableEnvironment 中执行一条 DESCRIBE 语句。
可以使用 TableEnvironment 的 executeSql() 方法执行 DESCRIBE 语句。如果 DESCRIBE 操作执行成功，executeSql() 方法会返回所有对象，否则会抛出异常。
以下示例展示了如何在 TableEnvironment 中执行一条 DESCRIBE 语句。
可以使用 TableEnvironment 的 execute_sql() 方法执行 DESCRIBE 语句。如果 DESCRIBE 操作执行成功，execute_sql() 方法会返回所有对象，否则会抛出异常。
以下示例展示了如何在 TableEnvironment 中执行一条 DESCRIBE 语句。
DESCRIBE 语句可以在 SQL CLI 中执行。
以下示例展示了如何在 SQL CLI 中执行一条 DESCRIBE 语句。
TableEnvironment tableEnv = TableEnvironment.create(...);
// 注册名为 “Orders” 的表
tableEnv.executeSql(
"CREATE TABLE Orders (" +
" `user` BIGINT NOT NULl comment 'this is primary key'," +
" product VARCHAR(32)," +
" amount INT," +
" ts TIMESTAMP(3) comment 'notice: watermark'," +
" ptime AS PROCTIME() comment 'this is a computed column'," +
" PRIMARY KEY(`user`) NOT ENFORCED," +
" WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS" +
") with (...)");
// 打印 schema
tableEnv.executeSql("DESCRIBE Orders").print();
// 打印 schema
tableEnv.executeSql("DESC Orders").print();
// 注册名为 “cat2” 的 catalog
tableEnv.executeSql("CREATE CATALOG cat2 WITH ('type'='generic_in_memory', 'default-database'='db')");
// 打印元数据
tableEnv.executeSql("DESCRIBE CATALOG cat2").print();
// 打印完整的元数据
tableEnv.executeSql("DESC CATALOG EXTENDED cat2").print();
val tableEnv = TableEnvironment.create(...)
// 注册名为 “Orders” 的表
tableEnv.executeSql(
"CREATE TABLE Orders (" +
" `user` BIGINT NOT NULl comment 'this is primary key'," +
" product VARCHAR(32)," +
" amount INT," +
" ts TIMESTAMP(3) comment 'notice: watermark'," +
" ptime AS PROCTIME() comment 'this is a computed column'," +
" PRIMARY KEY(`user`) NOT ENFORCED," +
" WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS" +
") with (...)")
// 打印 schema
tableEnv.executeSql("DESCRIBE Orders").print()
// 打印 schema
tableEnv.executeSql("DESC Orders").print()
// 注册名为 “cat2” 的 catalog
tableEnv.executeSql("CREATE CATALOG cat2 WITH ('type'='generic_in_memory', 'default-database'='db')")
// 打印元数据
tableEnv.executeSql("DESCRIBE CATALOG cat2").print()
// 打印完整的元数据
tableEnv.executeSql("DESC CATALOG EXTENDED cat2").print()
table_env = TableEnvironment.create(...)
# 注册名为 “Orders” 的表
table_env.execute_sql( \
"CREATE TABLE Orders ("
" `user` BIGINT NOT NULl comment 'this is primary key',"
" product VARCHAR(32),"
" amount INT,"
" ts TIMESTAMP(3) comment 'notice: watermark',"
" ptime AS PROCTIME() comment 'this is a computed column',"
" PRIMARY KEY(`user`) NOT ENFORCED,"
" WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS"
") with (...)");
# 打印 schema
table_env.execute_sql("DESCRIBE Orders").print()
# 打印 schema
table_env.execute_sql("DESC Orders").print()
# 注册名为 “cat2” 的 catalog
table_env.execute_sql("CREATE CATALOG cat2 WITH ('type'='generic_in_memory', 'default-database'='db')")
# 打印元数据
table_env.execute_sql("DESCRIBE CATALOG cat2").print()
# 打印完整的元数据
table_env.execute_sql("DESC CATALOG EXTENDED cat2").print()
Flink SQL> CREATE TABLE Orders (
> `user` BIGINT NOT NULl comment 'this is primary key',
> product VARCHAR(32),
> amount INT,
> ts TIMESTAMP(3) comment 'notice: watermark',
> ptime AS PROCTIME() comment 'this is a computed column',
> PRIMARY KEY(`user`) NOT ENFORCED,
> WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS
> ) with (
> ...
> );
[INFO] Table has been created.
Flink SQL> DESCRIBE Orders;
Flink SQL> DESC Orders;
Flink SQL> CREATE CATALOG cat2 WITH ('type'='generic_in_memory', 'default-database'='db');
[INFO] Execute statement succeeded.
Flink SQL> DESCRIBE CATALOG cat2;
Flink SQL> DESC CATALOG EXTENDED cat2;
Flink SQL> DESCRIBE JOB '228d70913eab60dda85c5e7f78b5782c';
Flink SQL> DESC JOB '228d70913eab60dda85c5e7f78b5782c';
上述示例的结果是：
# DESCRIBE TABLE Orders
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| name | type | null | key | extras | watermark | comment |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| user | BIGINT | FALSE | PRI(user) | | | this is primary key |
| product | VARCHAR(32) | TRUE | | | | |
| amount | INT | TRUE | | | | |
| ts | TIMESTAMP(3) *ROWTIME* | TRUE | | | `ts` - INTERVAL '1' SECOND | notice: watermark |
| ptime | TIMESTAMP_LTZ(3) *PROCTIME* | FALSE | | AS PROCTIME() | | this is a computed column |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
5 rows in set
# DESCRIBE CATALOG cat2
+-----------+-------------------+
| info name | info value |
+-----------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
+-----------+-------------------+
3 rows in set
# DESCRIBE CATALOG EXTENDED cat2
+-------------------------+-------------------+
| info name | info value |
+-------------------------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
| option:default-database | db |
+-------------------------+-------------------+
4 rows in set
# DESCRIBE TABLE Orders
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| name | type | null | key | extras | watermark | comment |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| user | BIGINT | FALSE | PRI(user) | | | this is primary key |
| product | VARCHAR(32) | TRUE | | | | |
| amount | INT | TRUE | | | | |
| ts | TIMESTAMP(3) *ROWTIME* | TRUE | | | `ts` - INTERVAL '1' SECOND | notice: watermark |
| ptime | TIMESTAMP_LTZ(3) *PROCTIME* | FALSE | | AS PROCTIME() | | this is a computed column |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
5 rows in set
# DESCRIBE CATALOG cat2
+-----------+-------------------+
| info name | info value |
+-----------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
+-----------+-------------------+
3 rows in set
# DESCRIBE CATALOG EXTENDED cat2
+-------------------------+-------------------+
| info name | info value |
+-------------------------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
| option:default-database | db |
+-------------------------+-------------------+
4 rows in set
# DESCRIBE TABLE Orders
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| name | type | null | key | extras | watermark | comment |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| user | BIGINT | FALSE | PRI(user) | | | this is primary key |
| product | VARCHAR(32) | TRUE | | | | |
| amount | INT | TRUE | | | | |
| ts | TIMESTAMP(3) *ROWTIME* | TRUE | | | `ts` - INTERVAL '1' SECOND | notice: watermark |
| ptime | TIMESTAMP_LTZ(3) *PROCTIME* | FALSE | | AS PROCTIME() | | this is a computed column |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
5 rows in set
# DESCRIBE CATALOG cat2
+-----------+-------------------+
| info name | info value |
+-----------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
+-----------+-------------------+
3 rows in set
# DESCRIBE CATALOG EXTENDED cat2
+-------------------------+-------------------+
| info name | info value |
+-------------------------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
| option:default-database | db |
+-------------------------+-------------------+
4 rows in set
# DESCRIBE TABLE Orders
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| name | type | null | key | extras | watermark | comment |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
| user | BIGINT | FALSE | PRI(user) | | | this is primary key |
| product | VARCHAR(32) | TRUE | | | | |
| amount | INT | TRUE | | | | |
| ts | TIMESTAMP(3) *ROWTIME* | TRUE | | | `ts` - INTERVAL '1' SECOND | notice: watermark |
| ptime | TIMESTAMP_LTZ(3) *PROCTIME* | FALSE | | AS PROCTIME() | | this is a computed column |
+---------+-----------------------------+-------+-----------+---------------+----------------------------+---------------------------+
5 rows in set
# DESCRIBE CATALOG cat2
+-----------+-------------------+
| info name | info value |
+-----------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
+-----------+-------------------+
3 rows in set
# DESCRIBE CATALOG EXTENDED cat2
+-------------------------+-------------------+
| info name | info value |
+-------------------------+-------------------+
| name | cat2 |
| type | generic_in_memory |
| comment | |
| option:default-database | db |
+-------------------------+-------------------+
4 rows in set
# DESCRIBE JOB '228d70913eab60dda85c5e7f78b5782c'
+----------------------------------+----------+---------+-------------------------+
| job id | job name | status | start time |
+----------------------------------+----------+---------+-------------------------+
| 228d70913eab60dda85c5e7f78b5782c | myjob | RUNNING | 2023-02-11T05:03:51.523 |
+----------------------------------+----------+---------+-------------------------+
1 row in set
语法 #
DESCRIBE TABLE #
{ DESCRIBE | DESC } [catalog_name.][db_name.]table_name
DESCRIBE CATALOG #
{ DESCRIBE | DESC } CATALOG [EXTENDED] catalog_name
DESCRIBE JOB #
{ DESCRIBE | DESC } JOB '<job_id>'
Attention DESCRIBE JOB 语句仅适用于 SQL CLI 或者 SQL Gateway.