fix: generated column PK and NULL handling

internal/diff/table.go

@@ -590,10 +590,9 @@ func (td *tableDiff) generateAlterTableStatements(targetSchema string, collector
 			stmt += fmt.Sprintf(" DEFAULT %s", *column.DefaultValue)
 		}
 
-		// Don't add NOT NULL for identity columns or SERIAL columns as they are implicitly NOT NULL
+		// Don't add NOT NULL for identity columns, SERIAL columns, or generated columns as they are implicitly NOT NULL
 		// Also skip NOT NULL if we're adding PRIMARY KEY inline (PRIMARY KEY implies NOT NULL)
-		// For generated columns, include NOT NULL if explicitly specified (but before GENERATED clause)
-		if !column.IsNullable && column.Identity == nil && !isSerialColumn(column) && pkConstraint == nil {
+		if !column.IsNullable && column.Identity == nil && !isSerialColumn(column) && pkConstraint == nil && !column.IsGenerated {
 			stmt += " NOT NULL"
 		}
 
@@ -607,14 +606,19 @@ func (td *tableDiff) generateAlterTableStatements(targetSchema string, collector
 			}
 		}
 
+		// Add PRIMARY KEY inline before generated column syntax (PostgreSQL requires this order)
+		if pkConstraint != nil && column.IsGenerated {
+			stmt += " PRIMARY KEY"
+		}
+
 		// Add generated column syntax
 		if column.IsGenerated && column.GeneratedExpr != nil {
 			// TODO: Add support for GENERATED ALWAYS AS (...) VIRTUAL when PostgreSQL 18 is supported
 			stmt += fmt.Sprintf(" GENERATED ALWAYS AS (%s) STORED", *column.GeneratedExpr)
 		}
 
-		// Add PRIMARY KEY inline if present
-		if pkConstraint != nil {
+		// Add PRIMARY KEY inline if present (for non-generated columns)
+		if pkConstraint != nil && !column.IsGenerated {
 			stmt += " PRIMARY KEY"
 		}
 

ir/parser.go

@@ -763,8 +763,6 @@ func (p *Parser) parseColumnDef(colDef *pg_query.ColumnDef, position int, schema
 					if generatedExpr != "" {
 						column.GeneratedExpr = &generatedExpr
 						column.IsGenerated = true
-						// Generated columns are implicitly NOT NULL
-						column.IsNullable = false
 					}
 				}
 			}

testdata/diff/create_table/add_column_generated/diff.sql

@@ -1 +1,3 @@
-ALTER TABLE merge_request ADD COLUMN iid integer NOT NULL GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;
+ALTER TABLE merge_request
+ADD COLUMN iid integer PRIMARY KEY GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;
+ALTER TABLE merge_request ADD COLUMN title text GENERATED ALWAYS AS (data ->> 'title') STORED;

testdata/diff/create_table/add_column_generated/new.sql

@@ -1,4 +1,5 @@
 CREATE TABLE public.merge_request (
     data jsonb NOT NULL,
-    iid integer NOT NULL GENERATED ALWAYS AS ((data ->> 'iid')::integer) STORED
+    iid integer PRIMARY KEY GENERATED ALWAYS AS ((data ->> 'iid')::integer) STORED,
+    title text GENERATED ALWAYS AS (data ->> 'title') STORED
 );

testdata/diff/create_table/add_column_generated/plan.json

@@ -1,6 +1,6 @@
 {
   "version": "1.0.0",
-  "pgschema_version": "1.1.1",
+  "pgschema_version": "1.2.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
     "hash": "67e51d7bd6b2b020d7a95dbe7f8e5f9bd9ec2e3f4068b9ed09bb63b79e656354"
@@ -9,10 +9,16 @@
     {
       "steps": [
         {
-          "sql": "ALTER TABLE merge_request ADD COLUMN iid integer NOT NULL GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;",
+          "sql": "ALTER TABLE merge_request\nADD COLUMN iid integer PRIMARY KEY GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;",
           "type": "table.column",
           "operation": "create",
           "path": "public.merge_request.iid"
+        },
+        {
+          "sql": "ALTER TABLE merge_request ADD COLUMN title text GENERATED ALWAYS AS (data ->> 'title') STORED;",
+          "type": "table.column",
+          "operation": "create",
+          "path": "public.merge_request.title"
         }
       ]
     }

testdata/diff/create_table/add_column_generated/plan.sql

@@ -1 +1,4 @@
-ALTER TABLE merge_request ADD COLUMN iid integer NOT NULL GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;
+ALTER TABLE merge_request
+ADD COLUMN iid integer PRIMARY KEY GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;
+
+ALTER TABLE merge_request ADD COLUMN title text GENERATED ALWAYS AS (data ->> 'title') STORED;

testdata/diff/create_table/add_column_generated/plan.txt

@@ -6,8 +6,12 @@ Summary by type:
 Tables:
   ~ merge_request
     + iid (column)
+    + title (column)
 
 DDL to be executed:
 --------------------------------------------------
 
-ALTER TABLE merge_request ADD COLUMN iid integer NOT NULL GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;
+ALTER TABLE merge_request
+ADD COLUMN iid integer PRIMARY KEY GENERATED ALWAYS AS (CAST(data ->> 'iid' AS int)) STORED;
+
+ALTER TABLE merge_request ADD COLUMN title text GENERATED ALWAYS AS (data ->> 'title') STORED;