[FLINK-10230][table] Support 'SHOW CREATE VIEW' syntax to print the q…

…uery of a view This closes apache#17352
mbalassi · Oct 26, 2021 · 0ed7847 · 0ed7847
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diff --git a/docs/content.zh/docs/dev/table/sql/show.md b/docs/content.zh/docs/dev/table/sql/show.md
@@ -27,8 +27,9 @@ under the License.
 # SHOW 语句
 
 
+SHOW 语句用于列出其相应父对象中的对象，例如 catalog、database、table 和 view、column、function 和 module。有关详细信息和其他选项，请参见各个命令。
 
-SHOW 语句用于列出所有的 catalog，或者列出当前 catalog 中所有的 database，或者列出当前 catalog 和当前 database 的所有表或视图，或者列出当前正在使用的 catalog 和 database, 或者列出创建指定表的语句，或者列出当前 catalog 和当前 database 中所有的 function，包括：系统 function 和用户定义的 function，或者仅仅列出当前 catalog 和当前 database 中用户定义的 function，或者列出当前环境所有激活的 module，或者列出当前环境所有加载的 module 及激活状态，或者根据可选的模糊查询语句列出给定表或视图的相应列。
+SHOW CREATE 语句用于打印给定对象的创建 DDL 语句。当前的 SHOW CREATE 语句仅在打印给定表和视图的 DDL 语句时可用。
 
 目前 Flink SQL 支持下列 SHOW 语句：
 - SHOW CATALOGS
@@ -39,6 +40,7 @@ SHOW 语句用于列出所有的 catalog，或者列出当前 catalog 中所有
 - SHOW CREATE TABLE
 - SHOW COLUMNS
 - SHOW VIEWS
+- SHOW CREATE VIEW
 - SHOW FUNCTIONS
 - SHOW MODULES
 - SHOW FULL MODULES
@@ -132,7 +134,7 @@ tEnv.executeSql("SHOW CREATE TABLE my_table").print();
 // )
 
 // show columns
-tEnv.executeSql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print();
+tEnv.executeSql("SHOW COLUMNS FROM my_table LIKE '%f%'").print();
 // +--------+-------+------+-----+--------+-----------+
 // | name | type | null | key | extras | watermark |
 // +--------+-------+------+-----+--------+-----------+
@@ -141,7 +143,7 @@ tEnv.executeSql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print();
 
 
 // create a view
-tEnv.executeSql("CREATE VIEW my_view AS ...");
+tEnv.executeSql("CREATE VIEW my_view AS SELECT * FROM my_table");
 // show views
 tEnv.executeSql("SHOW VIEWS").print();
 // +-----------+
@@ -150,6 +152,12 @@ tEnv.executeSql("SHOW VIEWS").print();
 // | my_view |
 // +-----------+
 
+// show create view
+tEnv.executeSql("SHOW CREATE VIEW my_view").print();
+// CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+// SELECT *
+// FROM `default_catalog`.`default_database`.`my_table`
+
 // show functions
 tEnv.executeSql("SHOW FUNCTIONS").print();
 // +---------------+
@@ -230,15 +238,15 @@ tEnv.executeSql("SHOW CREATE TABLE my_table").print()
 // )
 
 // show columns
-tEnv.executeSql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print()
+tEnv.executeSql("SHOW COLUMNS FROM my_table LIKE '%f%'").print()
 // +--------+-------+------+-----+--------+-----------+
 // | name | type | null | key | extras | watermark |
 // +--------+-------+------+-----+--------+-----------+
 // | field2 | BYTES | true | | | |
 // +--------+-------+------+-----+--------+-----------+
 
 // create a view
-tEnv.executeSql("CREATE VIEW my_view AS ...")
+tEnv.executeSql("CREATE VIEW my_view AS SELECT * FROM my_table")
 // show views
 tEnv.executeSql("SHOW VIEWS").print()
 // +-----------+
@@ -247,6 +255,12 @@ tEnv.executeSql("SHOW VIEWS").print()
 // | my_view |
 // +-----------+
 
+// show create view
+tEnv.executeSql("SHOW CREATE VIEW my_view").print();
+// CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+// SELECT *
+// FROM `default_catalog`.`default_database`.`my_table`
+
 // show functions
 tEnv.executeSql("SHOW FUNCTIONS").print()
 // +---------------+
@@ -325,15 +339,15 @@ table_env.executeSql("SHOW CREATE TABLE my_table").print()
 # )
 
 # show columns
-table_env.execute_sql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print()
+table_env.execute_sql("SHOW COLUMNS FROM my_table LIKE '%f%'").print()
 # +--------+-------+------+-----+--------+-----------+
 # | name | type | null | key | extras | watermark |
 # +--------+-------+------+-----+--------+-----------+
 # | field2 | BYTES | true | | | |
 # +--------+-------+------+-----+--------+-----------+
 
 # create a view
-table_env.execute_sql("CREATE VIEW my_view AS ...")
+table_env.execute_sql("CREATE VIEW my_view AS SELECT * FROM my_table")
 # show views
 table_env.execute_sql("SHOW VIEWS").print()
 # +-----------+
@@ -342,6 +356,12 @@ table_env.execute_sql("SHOW VIEWS").print()
 # | my_view |
 # +-----------+
 
+# show create view
+table_env.execute_sql("SHOW CREATE VIEW my_view").print()
+# CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+# SELECT *
+# FROM `default_catalog`.`default_database`.`my_table`
+
 # show functions
 table_env.execute_sql("SHOW FUNCTIONS").print()
 # +---------------+
@@ -414,12 +434,17 @@ Flink SQL> SHOW COLUMNS from MyUserTable LIKE '%f%';
 1 row in set
 
 
-Flink SQL> CREATE VIEW my_view AS ...;
+Flink SQL> CREATE VIEW my_view AS SELECT * from my_table;
 [INFO] View has been created.
 
 Flink SQL> SHOW VIEWS;
 my_view
 
+Flink SQL> SHOW CREATE VIEW my_view;
+CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+SELECT *
+FROM `default_catalog`.`default_database`.`my_table`
+
 Flink SQL> SHOW FUNCTIONS;
 mod
 sha256
@@ -606,6 +631,14 @@ SHOW VIEWS
 
 展示当前 catalog 和当前 database 中所有的视图。
 
+## SHOW CREATE VIEW
+
+```sql
+SHOW CREATE VIEW [catalog_name.][db_name.]view_name
+```
+
+展示创建指定视图的 create 语句。
+
 ## SHOW FUNCTIONS
 
 ```sql

diff --git a/docs/content/docs/dev/table/sql/show.md b/docs/content/docs/dev/table/sql/show.md
@@ -26,7 +26,9 @@ under the License.
 
 # SHOW Statements
 
-SHOW statements are used to list all catalogs, or list all databases in the current catalog, or list all tables/views in the current catalog and the current database, or show current catalog and database, or show create statement for specified table, or list all functions including system functions and user-defined functions in the current catalog and current database, or list only user-defined functions in the current catalog and current database, or list enabled module names, or list all loaded modules with enabled status in the current session, or list the columns of the table or the view with the given name and the optional like clause.
+SHOW statements are used to list objects within their corresponding parent, such as catalogs, databases, tables and views, columns, functions, and modules. See the individual commands for more details and additional options.
+
+SHOW CREATE statements are used to print a DDL statement with which a given object can be created. The currently 'SHOW CREATE' statement is only available in printing DDL statement of the given table and view.
 
 Flink SQL supports the following SHOW statements for now:
 - SHOW CATALOGS
@@ -37,6 +39,7 @@ Flink SQL supports the following SHOW statements for now:
 - SHOW CREATE TABLE
 - SHOW COLUMNS
 - SHOW VIEWS
+- SHOW CREATE VIEW
 - SHOW FUNCTIONS
 - SHOW MODULES
 - SHOW JARS
@@ -131,7 +134,7 @@ tEnv.executeSql("SHOW CREATE TABLE my_table").print();
 // )
 
 // show columns
-tEnv.executeSql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print();
+tEnv.executeSql("SHOW COLUMNS FROM my_table LIKE '%f%'").print();
 // +--------+-------+------+-----+--------+-----------+
 // | name | type | null | key | extras | watermark |
 // +--------+-------+------+-----+--------+-----------+
@@ -140,7 +143,7 @@ tEnv.executeSql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print();
 
 
 // create a view
-tEnv.executeSql("CREATE VIEW my_view AS ...");
+tEnv.executeSql("CREATE VIEW my_view AS SELECT * FROM my_table");
 // show views
 tEnv.executeSql("SHOW VIEWS").print();
 // +-----------+
@@ -149,6 +152,12 @@ tEnv.executeSql("SHOW VIEWS").print();
 // | my_view |
 // +-----------+
 
+// show create view
+tEnv.executeSql("SHOW CREATE VIEW my_view").print();
+// CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+// SELECT *
+// FROM `default_catalog`.`default_database`.`my_table`
+
 // show functions
 tEnv.executeSql("SHOW FUNCTIONS").print();
 // +---------------+
@@ -229,15 +238,15 @@ tEnv.executeSql("SHOW CREATE TABLE my_table").print()
 // )
 
 // show columns
-tEnv.executeSql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print()
+tEnv.executeSql("SHOW COLUMNS FROM my_table LIKE '%f%'").print()
 // +--------+-------+------+-----+--------+-----------+
 // | name | type | null | key | extras | watermark |
 // +--------+-------+------+-----+--------+-----------+
 // | field2 | BYTES | true | | | |
 // +--------+-------+------+-----+--------+-----------+
 
 // create a view
-tEnv.executeSql("CREATE VIEW my_view AS ...")
+tEnv.executeSql("CREATE VIEW my_view AS SELECT * FROM my_table")
 // show views
 tEnv.executeSql("SHOW VIEWS").print()
 // +-----------+
@@ -246,6 +255,12 @@ tEnv.executeSql("SHOW VIEWS").print()
 // | my_view |
 // +-----------+
 
+// show create view
+tEnv.executeSql("SHOW CREATE VIEW my_view").print();
+// CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+// SELECT *
+// FROM `default_catalog`.`default_database`.`my_table`
+
 // show functions
 tEnv.executeSql("SHOW FUNCTIONS").print()
 // +---------------+
@@ -324,15 +339,15 @@ table_env.executeSql("SHOW CREATE TABLE my_table").print()
 # )
 
 # show columns
-table_env.execute_sql("SHOW COLUMNS FROM MY_TABLE LIKE '%f%'").print()
+table_env.execute_sql("SHOW COLUMNS FROM my_table LIKE '%f%'").print()
 # +--------+-------+------+-----+--------+-----------+
 # | name | type | null | key | extras | watermark |
 # +--------+-------+------+-----+--------+-----------+
 # | field2 | BYTES | true | | | |
 # +--------+-------+------+-----+--------+-----------+
 
 # create a view
-table_env.execute_sql("CREATE VIEW my_view AS ...")
+table_env.execute_sql("CREATE VIEW my_view AS SELECT * FROM my_table")
 # show views
 table_env.execute_sql("SHOW VIEWS").print()
 # +-----------+
@@ -341,6 +356,12 @@ table_env.execute_sql("SHOW VIEWS").print()
 # | my_view |
 # +-----------+
 
+# show create view
+table_env.execute_sql("SHOW CREATE VIEW my_view").print()
+# CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+# SELECT *
+# FROM `default_catalog`.`default_database`.`my_table`
+
 # show functions
 table_env.execute_sql("SHOW FUNCTIONS").print()
 # +---------------+
@@ -413,12 +434,17 @@ Flink SQL> SHOW COLUMNS from MyUserTable LIKE '%f%';
 1 row in set
 
 
-Flink SQL> CREATE VIEW my_view AS ...;
+Flink SQL> CREATE VIEW my_view AS SELECT * from my_table;
 [INFO] View has been created.
 
 Flink SQL> SHOW VIEWS;
 my_view
 
+Flink SQL> SHOW CREATE VIEW my_view;
+CREATE VIEW `default_catalog`.`default_db`.`my_view`(`field1`, `field2`, ...) as
+SELECT *
+FROM `default_catalog`.`default_database`.`my_table`
+
 Flink SQL> SHOW FUNCTIONS;
 mod
 sha256
@@ -605,6 +631,14 @@ SHOW VIEWS
 
 Show all views in the current catalog and the current database.
 
+## SHOW CREATE VIEW
+
+```sql
+SHOW CREATE VIEW [catalog_name.][db_name.]view_name
+```
+
+Show create view statement for specified view.
+
 ## SHOW FUNCTIONS
 
 ```sql

diff --git a/flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/CliClient.java b/flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/CliClient.java
@@ -36,6 +36,7 @@
 import org.apache.flink.table.operations.Operation;
 import org.apache.flink.table.operations.QueryOperation;
 import org.apache.flink.table.operations.ShowCreateTableOperation;
+import org.apache.flink.table.operations.ShowCreateViewOperation;
 import org.apache.flink.table.operations.UnloadModuleOperation;
 import org.apache.flink.table.operations.UseOperation;
 import org.apache.flink.table.operations.command.AddJarOperation;
@@ -443,6 +444,9 @@ private void callOperation(Operation operation, ExecutionMode mode) {
  } else if (operation instanceof ShowCreateTableOperation) {
  // SHOW CREATE TABLE
  callShowCreateTable((ShowCreateTableOperation) operation);
+ } else if (operation instanceof ShowCreateViewOperation) {
+ // SHOW CREATE VIEW
+ callShowCreateView((ShowCreateViewOperation) operation);
  } else {
  // fallback to default implementation
  executeOperation(operation);
@@ -593,6 +597,10 @@ public void callShowCreateTable(ShowCreateTableOperation operation) {
  printRawContent(operation);
  }
 
+ public void callShowCreateView(ShowCreateViewOperation operation) {
+ printRawContent(operation);
+ }
+
  public void printRawContent(Operation operation) {
  TableResult tableResult = executor.executeOperation(sessionId, operation);
  // show raw content instead of tableau style

diff --git a/flink-table/flink-sql-client/src/test/resources/sql/table.q b/flink-table/flink-sql-client/src/test/resources/sql/table.q
@@ -332,6 +332,12 @@ CREATE TABLE `default_catalog`.`default_database`.`orders2` (
 
 !ok
 
+# test SHOW CREATE VIEW for tables
+show create view orders2;
+[ERROR] Could not execute SQL statement. Reason:
+org.apache.flink.table.api.TableException: SHOW CREATE VIEW is only supported for views, but `default_catalog`.`default_database`.`orders2` is a table. Please use SHOW CREATE TABLE instead.
+!error
+
 # test explain plan to verify the table source cannot be created
 explain plan for select * from orders2;
 [ERROR] Could not execute SQL statement. Reason:

diff --git a/flink-table/flink-sql-client/src/test/resources/sql/view.q b/flink-table/flink-sql-client/src/test/resources/sql/view.q
@@ -51,6 +51,20 @@ create temporary view if not exists v2 as select * from v1;
 [INFO] Execute statement succeed.
 !info
 
+# test show create a temporary view
+show create view v1;
+CREATE TEMPORARY VIEW `default_catalog`.`default_database`.`v1`(`user`, `product`, `amount`, `ts`, `ptime`) as
+SELECT *
+FROM `default_catalog`.`default_database`.`orders`
+!ok
+
+# test show create a temporary view reference another view
+show create view v2;
+CREATE TEMPORARY VIEW `default_catalog`.`default_database`.`v2`(`user`, `product`, `amount`, `ts`, `ptime`) as
+SELECT *
+FROM `default_catalog`.`default_database`.`v1`
+!ok
+
 show tables;
 +------------+
 | table name |
@@ -75,7 +89,7 @@ show views;
 # test SHOW CREATE TABLE for views
 show create table v1;
 [ERROR] Could not execute SQL statement. Reason:
-org.apache.flink.table.api.TableException: SHOW CREATE TABLE does not support showing CREATE VIEW statement with identifier `default_catalog`.`default_database`.`v1`.
+org.apache.flink.table.api.TableException: SHOW CREATE TABLE is only supported for tables, but `default_catalog`.`default_database`.`v1` is a view. Please use SHOW CREATE VIEW instead.
 !error
 
 # ==== test permanent view =====
@@ -91,6 +105,23 @@ create view v1 as select * from orders;
 org.apache.flink.table.catalog.exceptions.TableAlreadyExistException: Table (or view) default_database.v1 already exists in Catalog default_catalog.
 !error
 
+# test show create a permanent view
+create view permanent_v1 as select * from orders;
+[INFO] Execute statement succeed.
+!info
+
+# test show create a permanent view
+show create view permanent_v1;
+CREATE VIEW `default_catalog`.`default_database`.`permanent_v1`(`user`, `product`, `amount`, `ts`, `ptime`) as
+SELECT *
+FROM `default_catalog`.`default_database`.`orders`
+!ok
+
+# remove permanent_v1 view
+drop view permanent_v1;
+[INFO] Execute statement succeed.
+!info
+
 # we didn't distinguish the temporary v1 and permanent v1 for now
 show views;
 +-----------+