diff --git a/extensions/functions_arithmetic.yaml b/extensions/functions_arithmetic.yaml
index a750df682..ffd43f4c4 100644
--- a/extensions/functions_arithmetic.yaml
+++ b/extensions/functions_arithmetic.yaml
@@ -362,3 +362,59 @@ aggregate_functions:
         decomposable: MANY
         intermediate: fp64?
         return: fp64?
+window_functions:
+  - name: "row_number"
+    description: "the number of the current row within its partition."
+    impls:
+      - args: []
+        nullability: DECLARED_OUTPUT
+        decomposable: NONE
+        return: i64?
+        window_type: PARTITION
+  - name: "rank"
+    description: "the rank of the current row, with gaps."
+    impls:
+      - args: []
+        nullability: DECLARED_OUTPUT
+        decomposable: NONE
+        return: i64?
+        window_type: PARTITION
+  - name: "dense_rank"
+    description: "the rank of the current row, without gaps."
+    impls:
+      - args: []
+        nullability: DECLARED_OUTPUT
+        decomposable: NONE
+        return: i64?
+        window_type: PARTITION
+  - name: "percent_rank"
+    description: "the relative rank of the current row."
+    impls:
+      - args: []
+        nullability: DECLARED_OUTPUT
+        decomposable: NONE
+        return: fp64?
+        window_type: PARTITION
+  - name: "cume_dist"
+    description: "the cumulative distribution."
+    impls:
+      - args: []
+        nullability: DECLARED_OUTPUT
+        decomposable: NONE
+        return: fp64?
+        window_type: PARTITION
+  - name: "ntile"
+    description: "Return an integer ranging from 1 to the argument value,dividing the partition as equally as possible."
+    impls:
+      - args:
+          - value: i32
+        nullability: DECLARED_OUTPUT  
+        decomposable: NONE
+        return: i32?
+        window_type: PARTITION
+      - args:
+          - value: i64
+        nullability: DECLARED_OUTPUT  
+        decomposable: NONE
+        return: i64?
+        window_type: PARTITION
diff --git a/text/simple_extensions_schema.yaml b/text/simple_extensions_schema.yaml
index 6fe274c78..911aa0bf7 100644
--- a/text/simple_extensions_schema.yaml
+++ b/text/simple_extensions_schema.yaml
@@ -45,6 +45,10 @@ properties:
     type: array
     items:
       $ref: "#/$defs/aggregateFunction"
+  window_functions:
+    type: array
+    items:
+      $ref: "#/$defs/windowFunction"
 
 $defs:
   type:
@@ -220,6 +224,7 @@ $defs:
               $ref: "#/$defs/maxset"
             decomposable:
               $ref: "#/$defs/decomposable"
+
   windowFunction:
     type: object
     additionalProperties: false
@@ -235,7 +240,7 @@ $defs:
         items:
           type: object
           additionalProperties: false
-          required: [ intermediate, return ]
+          required: [ return ]
           properties:
             args:
               $ref: "#/$defs/arguments"