Add support for :copyfrom in Python code generation

Author: kellen-miller

internal/endtoend/testdata/copyfrom/python/query.py

@@ -20,6 +20,11 @@
 """
 
 
+CREATE_AUTHORS_NAMED = """-- name: create_authors_named \\:copyfrom
+INSERT INTO authors (name, bio) VALUES (:p1, :p2)
+"""
+
+
 class Querier:
     def __init__(self, conn: sqlalchemy.engine.Connection):
         self._conn = conn
@@ -35,7 +40,11 @@ def create_author(self, *, name: str, bio: str) -> Optional[models.Author]:
         )
 
     def create_authors(self, arg_list: List[Any]) -> int:
-        result = self._conn.execute(sqlalchemy.text(CREATE_AUTHORS), arg_list)
+        result = self._conn.executemany(sqlalchemy.text(CREATE_AUTHORS), arg_list)
+        return result.rowcount
+
+    def create_authors_named(self, arg_list: List[Any]) -> int:
+        result = self._conn.executemany(sqlalchemy.text(CREATE_AUTHORS_NAMED), arg_list)
         return result.rowcount
 
 
@@ -54,5 +63,9 @@ async def create_author(self, *, name: str, bio: str) -> Optional[models.Author]
         )
 
     async def create_authors(self, arg_list: List[Any]) -> int:
-        result = await self._conn.execute(sqlalchemy.text(CREATE_AUTHORS), arg_list)
+        result = await self._conn.executemany(sqlalchemy.text(CREATE_AUTHORS), arg_list)
+        return result.rowcount
+
+    async def create_authors_named(self, arg_list: List[Any]) -> int:
+        result = await self._conn.executemany(sqlalchemy.text(CREATE_AUTHORS_NAMED), arg_list)
         return result.rowcount

internal/endtoend/testdata/copyfrom/sqlc.yaml

@@ -3,7 +3,7 @@ plugins:
   - name: py
     wasm:
       url: file://../../../../bin/sqlc-gen-python.wasm
-      sha256: "e9601f06d9e7d20e2908cf83b8e06688c426b148aead0ebeb282776cfb020b6b"
+      sha256: "32036421ce8137b6b1314a86069a04100fafc925627f132f38588e5b35ce8b54"
 sql:
   - schema: "schema.sql"
     queries: "query.sql"

internal/gen.go

@@ -211,11 +211,10 @@ func (q Query) ArgDictNode() *pyast.Node {
 }
 
 // BuildCopyFromBody generates the method body for :copyfrom commands.
-//
-// IMPORTANT: This implementation uses executemany for batch inserts, which is
-// faster than individual inserts but not as fast as PostgreSQL's native COPY.
-// For maximum performance with PostgreSQL, consider using psycopg's copy_from
-// directly via conn.connection.driver_connection.
+// This implementation explicitly uses executemany() for batch inserts, which is
+// significantly faster than individual inserts. For PostgreSQL specifically,
+// using the native COPY protocol would be even faster, but executemany provides
+// good performance while maintaining cross-database compatibility.
 func (q Query) BuildCopyFromBody(isAsync bool) []*pyast.Node {
 	var body []*pyast.Node
 
@@ -238,15 +237,18 @@ func (q Query) BuildCopyFromBody(isAsync bool) []*pyast.Node {
 		dataVar = argName
 	}
 
-	// Build the execute call with the SQL and parameter list
-	// SQLAlchemy detects the list and uses executemany internally
+	// Use executemany explicitly for batch inserts
+	// Build the SQL text object first
+	sqlText := poet.Node(&pyast.Call{
+		Func: poet.Attribute(poet.Name("sqlalchemy"), "text"),
+		Args: []*pyast.Node{poet.Name(q.ConstantName)},
+	})
+
+	// Call executemany with the SQL and parameter list
 	execCall := poet.Node(&pyast.Call{
-		Func: poet.Attribute(poet.Name("self._conn"), "execute"),
+		Func: poet.Attribute(poet.Name("self._conn"), "executemany"),
 		Args: []*pyast.Node{
-			poet.Node(&pyast.Call{
-				Func: poet.Attribute(poet.Name("sqlalchemy"), "text"),
-				Args: []*pyast.Node{poet.Name(q.ConstantName)},
-			}),
+			sqlText,
 			poet.Name(dataVar),
 		},
 	})