CREATE EXTERNAL TABLE

语法

CREATE EXTERNAL TABLE [IF NOT EXISTS] table_name
(column_name column_type[, …])
[PARTITIONED BY (column_name column_type[, …])]
ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
STORED AS {TEXTFILE|ORC|PARQUET|JSON|RCFILE|HUDI|ICEBERG|PAIMON}
LOCATION 'OSS_LOCATION';
[TBLPROPERTIES (
 'type' = 'cow|mor'
 'auto.create.location' = 'true|false')
 'metadata_location' = 'METADATA_LOCATION')]

参数说明

示例

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.osstest6
(id int,
name string,
age int,
city string)
PARTITIONED BY (p2 string)
ROW FORMAT DELIMITED FIELDS TERMINATED BY  ','
STORED AS TEXTFILE
LOCATION  'oss://testBucketName/osstest/p1=hangzhou/';

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.osstest7
(id int,
name string,
age int,
city string)
PARTITIONED BY (p1 string,p2 string)
ROW FORMAT DELIMITED FIELDS TERMINATED BY  ','
STORED AS TEXTFILE
LOCATION  'oss://testBucketName/osstest/';

语法

CREATE EXTERNAL TABLE [IF NOT EXISTS] table_name
(column_name column_type[, …])
ENGINE='MYSQL'
TABLE_PROPERTIES='{  
	"url":"mysql_vpc_address",  
	"tablename":"mysql_table_name",  
	"username":"mysql_user_name",  
	"password":"mysql_user_password"
	[,"charset":"{gbk|utf8|utf8mb4}"]
  }';

参数说明

示例

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.mysqltest (
	id int,
	name varchar(1023),
	age int
 ) ENGINE = 'MYSQL'
 TABLE_PROPERTIES = '{
   "url":"jdbc:mysql://rm-bp1gx6********.mysql.rds.aliyuncs.com:3306/test_adb",
   "tablename":"person",
   "username":"testUserName",
   "password":"testUserPassword",
   "charset":"utf8"
}';

语法

CREATE EXTERNAL TABLE [IF NOT EXISTS] table_name
(column_name column_type[, …])
ENGINE='MONGODB'
TABLE_PROPERTIES = '{
	"mapped_name":"table",
  "location":"location",
  "username":"user",
  "password":"password",
}';

参数说明

示例

CREATE EXTERNAL TABLE adb_external_demo.mongodbtest (
  id int,
  name string,
  age int
) ENGINE = 'MONGODB' TABLE_PROPERTIES ='{
"mapped_name":"person",
"location":"mongodb://testuser:****@dds-bp113d414bca8****.mongodb.rds.aliyuncs.com:3717,dds-bp113d414bca8****.mongodb.rds.aliyuncs.com:3717/test_mongodb",
"username":"testuser",
"password":"password",
}';

语法

CREATE EXTERNAL TABLE [IF NOT EXISTS] table_name
(column_name column_type[, …])
ENGINE='OTS'
TABLE_PROPERTIES = '{
	"mapped_name":"table_name",
	"location":"tablestore_vpc_address"
}';

参数说明

示例

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.otstest (
	id int,
	name string,
	age int
) ENGINE = 'OTS' 
TABLE_PROPERTIES = '{
	"mapped_name":"person",
	"location":"https://w0****la.cn-hangzhou.vpc.tablestore.aliyuncs.com"
}';

语法

CREATE EXTERNAL TABLE [IF NOT EXISTS] table_name
(column_name column_type[, …])
ENGINE='ODPS'
TABLE_PROPERTIES='{
	"endpoint":"endpoint",
	"accessid":"accesskey_id",
	"accesskey":"accesskey_secret",
	["partition_column":"partition_column"],
	"project_name":"project_name",
	"table_name":"table_name",
	["auto_refresh":"true|false"],
	["auto_refresh_mode":"add_only|full"]
}';

参数说明

示例

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.mctest (
	id int,
	name varchar(1023),
	age int,
	dt string
) ENGINE='ODPS'
TABLE_PROPERTIES='{
	"accessid":"LTAI****************",
	"endpoint":"http://service.cn-hangzhou.maxcompute.aliyun.com/api",
	"accesskey":"yourAccessKeySecret",
	"partition_column":"dt",
	"project_name":"test_adb",
	"table_name":"person"
}';

Schema 自动刷新（auto refresh）

MaxCompute外表支持Schema自动刷新：开启后，会按刷新周期自动将MaxCompute源表的表结构变化同步到外表，无需重建外表或手动刷新。是否开启及刷新范围由建表时的auto_refresh、auto_refresh_mode参数控制，参见上文参数说明。

集群级配置

在使用表级auto_refresh=true开启Schema自动刷新前，需先执行以下命令开启集群级自动刷新开关。

-- 开启Schema自动刷新功能。
SET ADB_CONFIG external_table_schema_refresh_enabled=true;

-- Schema自动刷新的轮询间隔，单位为毫秒，默认值为300000（即5分钟）。该配置需重启集群后生效。
SET ADB_CONFIG external_table_schema_refresh_poll_interval_ms=300000;

示例

以下示例创建一张开启Schema自动刷新、刷新模式为add_only的MaxCompute外表：

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.mctest_add_only (
	id BIGINT,
	name VARCHAR(1024),
	amount DOUBLE
) ENGINE='ODPS'
TABLE_PROPERTIES='{
	"accessid":"LTAI****************",
	"accesskey":"yourAccessKeySecret",
	"endpoint":"https://service.cn-hangzhou-vpc.maxcompute.aliyun-inc.com/api",
	"project_name":"test_adb",
	"table_name":"person",
	"auto_refresh":"true",
	"auto_refresh_mode":"add_only"
}';

MaxCompute源表新增列后，外表会在下一轮刷新后自动新增对应列；源表删除列或列类型变化不会自动应用。

以下示例创建一张开启Schema自动刷新、刷新模式为full的MaxCompute外表：

CREATE EXTERNAL TABLE IF NOT EXISTS adb_external_demo.mctest_full (
	id BIGINT,
	name VARCHAR(1024),
	amount DOUBLE
) ENGINE='ODPS'
TABLE_PROPERTIES='{
	"accessid":"LTAI****************",
	"accesskey":"yourAccessKeySecret",
	"endpoint":"https://service.cn-hangzhou-vpc.maxcompute.aliyun-inc.com/api",
	"project_name":"test_adb",
	"table_name":"person",
	"auto_refresh":"true",
	"auto_refresh_mode":"full"
}';

MaxCompute源表新增列、删除列或列类型变化后，外表会在下一轮刷新后同步更新元数据。

注意事项

• Schema自动刷新能力仅适用于ENGINE='ODPS'的MaxCompute外表。

• add_only为默认模式，适用于生产环境中仅允许新增列的场景。

• full模式会自动同步源表的删除列和列类型变化，可能影响依赖旧列的SQL、应用程序、报表或视图，请谨慎使用。

• 如果基于 MaxCompute 外表创建了视图且使用了*（例如CREATE VIEW view_name AS SELECT * FROM external_table），视图在创建时会将其展开并保存为固定的列列表。当 full 模式同步源表的删除列或列名变化、且涉及视图已保存的列时，查询该视图会报错并提示视图失效、需重新创建，这属于预期行为。建议避免在视图中使用*。更多信息，请参见注意事项。