[FLINK-21579][table-api] Support "SHOW USER FUNCTIONS" statement in T…

…able API and SQL Client

This closes apache#15110

docs/content.zh/docs/dev/table/sql/show.md

@@ -28,7 +28,7 @@ under the License.
 
 
 
-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, 或者列出所有的 function，包括：临时系统 function，系统 function，临时 catalog function，当前 catalog 和 database 中的 catalog function。
+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。
 
 目前 Flink SQL 支持下列 SHOW 语句：
 - SHOW CATALOGS
@@ -138,6 +138,17 @@ tEnv.executeSql("SHOW FUNCTIONS").print();
 // | ... |
 // +---------------+
 
+// create a user defined function
+tEnv.executeSql("CREATE FUNCTION f1 AS ...");
+// show user defined functions
+tEnv.executeSql("SHOW USER FUNCTIONS").print();
+// +---------------+
+// | function name |
+// +---------------+
+// | f1 |
+// | ... |
+// +---------------+
+
 ```
 {{< /tab >}}
 {{< tab "Scala" >}}
@@ -191,6 +202,17 @@ tEnv.executeSql("SHOW FUNCTIONS").print()
 // | ... |
 // +---------------+
 
+// create a user defined function
+tEnv.executeSql("CREATE FUNCTION f1 AS ...")
+// show user defined functions
+tEnv.executeSql("SHOW USER FUNCTIONS").print()
+// +---------------+
+// | function name |
+// +---------------+
+// | f1 |
+// | ... |
+// +---------------+
+
 ```
 {{< /tab >}}
 {{< tab "Python" >}}
@@ -244,6 +266,17 @@ table_env.execute_sql("SHOW FUNCTIONS").print()
 # | ... |
 # +---------------+
 
+# create a user defined function
+table_env.execute_sql("CREATE FUNCTION f1 AS ...")
+# show user defined functions
+table_env.execute_sql("SHOW USER FUNCTIONS").print()
+# +---------------+
+# | function name |
+# +---------------+
+# | f1 |
+# | ... |
+# +---------------+
+
 ```
 {{< /tab >}}
 {{< tab "SQL CLI" >}}
@@ -272,6 +305,13 @@ mod
 sha256
 ...
 
+Flink SQL> CREATE FUNCTION f1 AS ...;
+[INFO] Function has been created.
+
+Flink SQL> SHOW USER FUNCTIONS;
+f1
+...
+
 ```
 {{< /tab >}}
 {{< /tabs >}}
@@ -329,7 +369,10 @@ SHOW VIEWS
 ## SHOW FUNCTIONS
 
 ```sql
-SHOW FUNCTIONS
+SHOW [USER] FUNCTIONS
 ```
 
-展示所有的 function，包括：临时系统 function, 系统 function, 临时 catalog function，当前 catalog 和 database 中的 catalog function。
+展示当前 catalog 和当前 database 中所有的 function，包括：系统 function 和用户定义的 function。
+
+**USER**
+仅仅展示当前 catalog 和当前 database 中用户定义的 function。

docs/content/docs/dev/table/sql/show.md

@@ -26,7 +26,7 @@ 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 list all functions including temp system functions, system functions, temp catalog functions and catalog functions in the current catalog and the current database.
+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 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.
 
 Flink SQL supports the following SHOW statements for now:
 - SHOW CATALOGS
@@ -138,6 +138,17 @@ tEnv.executeSql("SHOW FUNCTIONS").print();
 // | ... |
 // +---------------+
 
+// create a user defined function
+tEnv.executeSql("CREATE FUNCTION f1 AS ...");
+// show user defined functions
+tEnv.executeSql("SHOW USER FUNCTIONS").print();
+// +---------------+
+// | function name |
+// +---------------+
+// | f1 |
+// | ... |
+// +---------------+
+
 ```
 {{< /tab >}}
 {{< tab "Scala" >}}
@@ -191,6 +202,17 @@ tEnv.executeSql("SHOW FUNCTIONS").print()
 // | ... |
 // +---------------+
 
+// create a user defined function
+tEnv.executeSql("CREATE FUNCTION f1 AS ...")
+// show user defined functions
+tEnv.executeSql("SHOW USER FUNCTIONS").print()
+// +---------------+
+// | function name |
+// +---------------+
+// | f1 |
+// | ... |
+// +---------------+
+
 ```
 {{< /tab >}}
 {{< tab "Python" >}}
@@ -244,6 +266,17 @@ table_env.execute_sql("SHOW FUNCTIONS").print()
 # | ... |
 # +---------------+
 
+# create a user defined function
+table_env.execute_sql("CREATE FUNCTION f1 AS ...")
+# show user defined functions
+table_env.execute_sql("SHOW USER FUNCTIONS").print()
+# +---------------+
+# | function name |
+# +---------------+
+# | f1 |
+# | ... |
+# +---------------+
+
 ```
 {{< /tab >}}
 {{< tab "SQL CLI" >}}
@@ -272,6 +305,13 @@ mod
 sha256
 ...
 
+Flink SQL> CREATE FUNCTION f1 AS ...;
+[INFO] Function has been created.
+
+Flink SQL> SHOW USER FUNCTIONS;
+f1
+...
+
 ```
 {{< /tab >}}
 {{< /tabs >}}
@@ -329,7 +369,10 @@ Show all views in the current catalog and the current database.
 ## SHOW FUNCTIONS
 
 ```sql
-SHOW FUNCTIONS
+SHOW [USER] FUNCTIONS
 ```
 
-Show all functions including temp system functions, system functions, temp catalog functions and catalog functions in the current catalog and current database.
+Show all functions including system functions and user-defined functions in the current catalog and current database.
+
+**USER**
+Show only user-defined functions in the current catalog and current database.

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/CliClient.java

@@ -312,7 +312,7 @@ private void callCommand(SqlCommandCall cmdCall) {
  callShowViews();
  break;
  case SHOW_FUNCTIONS:
- callShowFunctions();
+ callShowFunctions(cmdCall);
  break;
  case SHOW_MODULES:
  callShowModules(cmdCall);
@@ -568,10 +568,10 @@ private void callShowViews() {
  terminal.flush();
  }
 
- private void callShowFunctions() {
+ private void callShowFunctions(SqlCommandCall cmdCall) {
  final List<String> functions;
  try {
- functions = getShowResult("FUNCTIONS");
+ functions = getShowResult(cmdCall);
  } catch (SqlExecutionException e) {
  printExecutionException(e);
  return;

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/CliStrings.java

@@ -89,7 +89,7 @@ private CliStrings() {
  .append(
  formatCommand(
  SqlCommand.SHOW_FUNCTIONS,
- "Shows all user-defined and built-in functions."))
+ "Shows all user-defined and built-in functions or only user-defined functions. Syntax: 'SHOW [USER] FUNCTIONS;'"))
  .append(formatCommand(SqlCommand.SHOW_TABLES, "Shows all registered tables."))
  .append(
  formatCommand(

flink-table/flink-sql-client/src/main/java/org/apache/flink/table/client/cli/SqlCommandParser.java

@@ -165,7 +165,6 @@ private static SqlCommandCall parseBySqlParser(Parser sqlParser, String stmt) {
  operands = new String[0];
  } else if (operation instanceof ShowFunctionsOperation) {
  cmd = SqlCommand.SHOW_FUNCTIONS;
- operands = new String[0];
  } else if (operation instanceof ShowPartitionsOperation) {
  cmd = SqlCommand.SHOW_PARTITIONS;
  } else if (operation instanceof CreateCatalogFunctionOperation

flink-table/flink-sql-client/src/test/java/org/apache/flink/table/client/cli/SqlCommandParserTest.java

@@ -334,6 +334,22 @@ public void testCommands() throws Exception {
  // show full modules
  TestItem.validSql(
  "SHOW FULL MODULES", SqlCommand.SHOW_MODULES, "SHOW FULL MODULES"),
+ // show functions
+ TestItem.validSql(
+ "SHOW FUNCTIONS;", SqlCommand.SHOW_FUNCTIONS, "SHOW FUNCTIONS"),
+ TestItem.validSql(
+ " SHOW FUNCTIONS ;",
+ SqlCommand.SHOW_FUNCTIONS,
+ "SHOW FUNCTIONS"),
+ // show user functions
+ TestItem.validSql(
+ "SHOW USER FUNCTIONS;",
+ SqlCommand.SHOW_FUNCTIONS,
+ "SHOW USER FUNCTIONS"),
+ TestItem.validSql(
+ " SHOW USER FUNCTIONS ;",
+ SqlCommand.SHOW_FUNCTIONS,
+ "SHOW USER FUNCTIONS"),
  // Test create function.
  TestItem.invalidSql(
  "CREATE FUNCTION ",