Add default_value under arguments

website/docs/docs/build/udfs.md

@@ -102,6 +102,7 @@ You can define SQL and Python UDFs in dbt. Note: Python UDFs are currently suppo
           - name: a_string          # required if arguments is specified
             data_type: string       # required if arguments is specified
             description: The string that I want to check if it's representing a positive integer (like "10") 
+            default_value: "'1'"    # optional, available in Snowflake and Postgres
         returns:                    # required
           data_type: integer        # required 
     ```
@@ -159,9 +160,10 @@ You can define SQL and Python UDFs in dbt. Note: Python UDFs are currently suppo
           arguments:                   # optional
             - name: a_string           # required if arguments is specified
               data_type: string        # required if arguments is specified
-              description: The string that I want to check if it's representing a positive integer (like "10") 
-          returns:                    # required
-            data_type: integer        # required
+              description: The string that I want to check if it's representing a positive integer (like "10")
+              default_value: "'1'"     # optional, available in Snowflake and Postgres
+          returns:                     # required
+            data_type: integer         # required
     ```
     </File>
     </TabItem>
@@ -197,7 +199,7 @@ You can define SQL and Python UDFs in dbt. Note: Python UDFs are currently suppo
     <TabItem value="Snowflake">
 
     ```sql
-    CREATE OR REPLACE FUNCTION udf_db.udf_schema.is_positive_int(a_string STRING)
+    CREATE OR REPLACE FUNCTION udf_db.udf_schema.is_positive_int(a_string STRING DEFAULT '1')
     RETURNS INTEGER
     LANGUAGE SQL
     IMMUTABLE
@@ -242,7 +244,7 @@ You can define SQL and Python UDFs in dbt. Note: Python UDFs are currently suppo
     <TabItem value="Postgres">
 
     ```sql
-    CREATE OR REPLACE FUNCTION udf_schema.is_positive_int(a_string text)
+    CREATE OR REPLACE FUNCTION udf_schema.is_positive_int(a_string text DEFAULT '1')
     RETURNS int
     LANGUAGE sql
     IMMUTABLE
@@ -260,7 +262,7 @@ You can define SQL and Python UDFs in dbt. Note: Python UDFs are currently suppo
 
     <TabItem value="Snowflake">
     ```sql
-    CREATE OR REPLACE FUNCTION udf_db.udf_schema.is_positive_int(a_string STRING)
+    CREATE OR REPLACE FUNCTION udf_db.udf_schema.is_positive_int(a_string STRING DEFAULT '1')
       RETURNS INTEGER
       LANGUAGE PYTHON
       RUNTIME_VERSION = '3.11'

website/docs/reference/function-properties.md

@@ -28,6 +28,7 @@ functions:
       - name: <string> # required if arguments is specified
         data_type: <string> # required if arguments is specified, warehouse-specific
         description: <markdown_string> # optional
+        default_value: <string | boolean | integer> # optional, available in Snowflake and Postgres
       - name: ... # declare additional arguments
     [returns](/reference/resource-properties/returns): # required
       data_type: <string> # required, warehouse-specific

website/docs/reference/resource-properties/function-arguments.md

@@ -10,13 +10,13 @@ import ArgumentsShared from '/snippets/_arguments-shared.md';
 
 ```yml
 
-
 functions:
   - name: <function name>
     arguments:
       - name: <arg name>
         data_type: <string> # warehouse-specific
         description: <markdown_string>
+        default_value: <string | boolean | integer> # optional, available in Snowflake and Postgres
 
 ```
 
@@ -55,6 +55,63 @@ Refer to your warehouse documentation for the complete list of supported data ty
 
 An optional markdown string describing the argument. This is helpful for documentation purposes.
 
+### default_value
+
+Use the `default_value` property to make a function argument optional.
+- When an argument isn't defined with a `default_value`, it becomes a required argument, and you must pass a value for them when you use the function. If a required argument isn’t passed, the function call fails.
+- Arguments with a `default_value` are optional &mdash; if you don't pass a value for the argument, the warehouse uses the value you set in `default_value`.
+
+This property is supported in [Snowflake](https://docs.snowflake.com/en/developer-guide/udf-stored-procedure-arguments#designating-an-argument-as-optional) and [Postgres](https://www.postgresql.org/docs/current/sql-createfunction.html). 
+
+When you use `default_value`, the order of your arguments matter. Any required arguments (those without default values) have to come before optional ones. Here's an example with the correct order: 
+
+<File name='functions/schema.yml'>
+
+```yml
+functions:
+  - name: sum_2_values
+    description: Add two values together
+    arguments:
+      - name: val1 # this argument comes first because it has no default value
+        data_type: integer
+        description: The first value
+      - name: val2
+        data_type: integer
+        description: The second value
+        default_value: 0 
+    returns:
+      data_type: integer
+```
+</File>
+
+In this example:
+- `val1` has no `default_value`, so it’s required.
+- `val2` has a `default_value` of `0`, so it’s optional. If you don’t provide a value for `val2`, the function uses `0` instead.
+
+See the following examples of calling the `sum_2_values` function in SQL and Python:
+
+<Tabs>
+
+<TabItem value="SQL">
+
+```sql
+select sum_2_values(5);        -- val1 = 5, val2 = 0 (default used since user didn't specify val2)
+select sum_2_values(5, 10);    -- val1 = 5, val2 = 10
+select sum_2_values();         -- ❌ error: val1 is required and must be passed
+```
+
+</TabItem>
+<TabItem value="Python">
+
+```py
+sum_2_values(5)                # val1 = 5, val2 = 0 (default used since user didn't specify val2)
+sum_2_values(5, 10)            # val1 = 5, val2 = 10
+sum_2_values()                 # ❌ error: val1 is required and must be passed
+```
+
+</TabItem>
+</Tabs>
+
 ## Examples
 
 ### Simple function arguments

website/snippets/_arguments-shared.md

@@ -1,2 +1,2 @@
-The `arguments` property is used to define the parameters that a resource can accept. Each argument can have a `name`, a type field, and an optional `description`.
+The `arguments` property is used to define the parameters that a resource can accept. Each argument can have a `name`, a type field, and optional properties such as `description` and `default_value`.