overwrite_condition should only work with overwrite mode, reverting support for append mode

Author: sfc-gh-mayliu

src/snowflake/snowpark/_internal/analyzer/snowflake_plan.py

@@ -1462,21 +1462,16 @@ def get_overwrite_delete_insert_plan(child: SnowflakePlan):
         if mode == SaveMode.APPEND:
             assert table_exists is not None
             if table_exists:
-                if overwrite_condition is not None:
-                    return get_overwrite_delete_insert_plan(child)
-                else:
-                    # Normal append without overwrite_condition
-                    return self.build(
-                        lambda x: insert_into_statement(
-                            table_name=full_table_name,
-                            child=x,
-                            column_names=column_names,
-                        ),
-                        child,
-                        source_plan,
-                    )
+                return self.build(
+                    lambda x: insert_into_statement(
+                        table_name=full_table_name,
+                        child=x,
+                        column_names=column_names,
+                    ),
+                    child,
+                    source_plan,
+                )
             else:
-                # Table doesn't exist, just create and insert (overwrite_condition is no-op)
                 return get_create_and_insert_plan(child, replace=False, error=False)
 
         elif mode == SaveMode.TRUNCATE:

src/snowflake/snowpark/dataframe_writer.py

@@ -333,7 +333,7 @@ def save_as_table(
                 Set to ``True`` if table exists, ``False`` if it doesn't, or ``None`` (default) for automatic detection.
                 Primarily useful for "append", "truncate", and "overwrite" with overwrite_condition modes to avoid running query for automatic detection.
             overwrite_condition: Specifies the overwrite condition to perform atomic targeted delete-insert.
-                Can be used when ``mode`` is "append" or "overwrite" when the table exists. Rows matching the
+                Can only be used when ``mode`` is "overwrite" and the table exists. Rows matching the
                 condition are deleted from the target table, then all rows from the DataFrame are inserted.
 
 
@@ -380,7 +380,7 @@ def save_as_table(
             [Row(ID=1, VAL='a'), Row(ID=2, VAL='b'), Row(ID=3, VAL='c')]
 
             >>> new_df = session.create_dataframe([[2, "updated2"], [5, "updated5"]], schema=["id", "val"])
-            >>> new_df.write.mode("append").save_as_table("my_table", overwrite_condition="id = 1 or val = 'b'")
+            >>> new_df.write.mode("overwrite").save_as_table("my_table", overwrite_condition="id = 1 or val = 'b'")
             >>> session.table("my_table").order_by("id").collect()
             [Row(ID=2, VAL='updated2'), Row(ID=3, VAL='c'), Row(ID=5, VAL='updated5')]
         """
@@ -513,13 +513,10 @@ def save_as_table(
                     f"Unsupported table type. Expected table types: {SUPPORTED_TABLE_TYPES}"
                 )
 
-            # overwrite_condition must be used with APPEND or OVERWRITE mode
-            if overwrite_condition is not None and save_mode not in (
-                SaveMode.APPEND,
-                SaveMode.OVERWRITE,
-            ):
+            # overwrite_condition must be used with OVERWRITE mode only
+            if overwrite_condition is not None and save_mode != SaveMode.OVERWRITE:
                 raise ValueError(
-                    f"'overwrite_condition' is only supported with mode='append' or mode='overwrite'. "
+                    f"'overwrite_condition' is only supported with mode='overwrite'. "
                     f"Got mode='{save_mode.value}'."
                 )