Add documentation for SHOW FUNCTIONS

apache · Dec 21, 2024 · 1352854 · 1352854
1 parent 4118c43
commit 1352854
Showing 1 changed file with 53 additions and 3 deletions.
diff --git a/docs/source/user-guide/sql/information_schema.md b/docs/source/user-guide/sql/information_schema.md
@@ -22,7 +22,10 @@
 DataFusion supports showing metadata about the tables and views available. This information can be accessed using the
 views of the ISO SQL `information_schema` schema or the DataFusion specific `SHOW TABLES` and `SHOW COLUMNS` commands.
 
-To show tables in the DataFusion catalog, use the `SHOW TABLES` command or the `information_schema.tables` view:
+## `SHOW TABLES`
+
+To show tables in the DataFusion catalog, use the `SHOW TABLES` command or the
+`information_schema.tables` view:
 
 ```sql
 > show tables;
@@ -39,7 +42,10 @@ or
 
 ```
 
-To show the schema of a table in DataFusion, use the `SHOW COLUMNS` command or the `information_schema.columns` view:
+## `SHOW COLUMNS`
+
+To show the schema of a table in DataFusion, use the `SHOW COLUMNS` command or
+the `information_schema.columns` view.
 
 ```sql
 > show columns from t;
@@ -52,7 +58,10 @@ or
 +---------------+--------------+------------+-------------+-----------+-------------+
 ```
 
-To show the current session configuration options, use the `SHOW ALL` command or the `information_schema.df_settings` view:
+## `SHOW ALL` (configuration options)
+
+To show the current session configuration options, use the `SHOW ALL` command or
+the `information_schema.df_settings` view:
 
 ```sql
 select * from information_schema.df_settings;
@@ -65,7 +74,48 @@ select * from information_schema.df_settings;
 | datafusion.execution.time_zone                  | UTC     |
 | datafusion.explain.logical_plan_only            | false   |
 | datafusion.explain.physical_plan_only           | false   |
+...
 | datafusion.optimizer.filter_null_join_keys      | false   |
 | datafusion.optimizer.skip_failed_rules          | true    |
 +-------------------------------------------------+---------+
 ```
+
+## `SHOW FUNCTIONS`
+
+To show the list of functions available, use the `SHOW FUNCTIONS` command or the
+
+- `information_schema.information_schema.routines` view: functions and descriptions
+- `information_schema.information_schema.parameters` view: parameters and descriptions
+
+Syntax:
+
+```sql
+SHOW FUNCTIONS [ LIKE <pattern> ];
+```
+
+Example output
+
+```sql
+> show functions like '%datetrunc';
++---------------+-------------------------------------+-------------------------+-------------------------------------------------+---------------+-------------------------------------------------------+-----------------------------------+
+| function_name | return_type                         | parameters              | parameter_types                                 | function_type | description                                           | syntax_example                    |
++---------------+-------------------------------------+-------------------------+-------------------------------------------------+---------------+-------------------------------------------------------+-----------------------------------+
+| datetrunc     | Timestamp(Microsecond, Some("+TZ")) | [precision, expression] | [Utf8, Timestamp(Microsecond, Some("+TZ"))]     | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Nanosecond, None)         | [precision, expression] | [Utf8View, Timestamp(Nanosecond, None)]         | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Second, Some("+TZ"))      | [precision, expression] | [Utf8View, Timestamp(Second, Some("+TZ"))]      | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Microsecond, None)        | [precision, expression] | [Utf8View, Timestamp(Microsecond, None)]        | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Second, None)             | [precision, expression] | [Utf8View, Timestamp(Second, None)]             | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Microsecond, None)        | [precision, expression] | [Utf8, Timestamp(Microsecond, None)]            | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Second, None)             | [precision, expression] | [Utf8, Timestamp(Second, None)]                 | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Microsecond, Some("+TZ")) | [precision, expression] | [Utf8View, Timestamp(Microsecond, Some("+TZ"))] | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Nanosecond, Some("+TZ"))  | [precision, expression] | [Utf8, Timestamp(Nanosecond, Some("+TZ"))]      | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Millisecond, None)        | [precision, expression] | [Utf8, Timestamp(Millisecond, None)]            | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Millisecond, Some("+TZ")) | [precision, expression] | [Utf8, Timestamp(Millisecond, Some("+TZ"))]     | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Second, Some("+TZ"))      | [precision, expression] | [Utf8, Timestamp(Second, Some("+TZ"))]          | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Nanosecond, None)         | [precision, expression] | [Utf8, Timestamp(Nanosecond, None)]             | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Millisecond, None)        | [precision, expression] | [Utf8View, Timestamp(Millisecond, None)]        | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Millisecond, Some("+TZ")) | [precision, expression] | [Utf8View, Timestamp(Millisecond, Some("+TZ"))] | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
+| datetrunc     | Timestamp(Nanosecond, Some("+TZ"))  | [precision, expression] | [Utf8View, Timestamp(Nanosecond, Some("+TZ"))]  | SCALAR        | Truncates a timestamp value to a specified precision. | date_trunc(precision, expression) |
++---------------+-------------------------------------+-------------------------+-------------------------------------------------+---------------+-------------------------------------------------------+-----------------------------------+
+16 row(s) fetched.
+```