fix: include column comments when adding new columns

internal/diff/table.go

@@ -766,6 +766,23 @@ func (td *tableDiff) generateAlterTableStatements(targetSchema string, collector
 		collector.collect(context, stmt+";")
 	}
 
+	// Add comments for new columns
+	for _, column := range td.AddedColumns {
+		if column.Comment != "" {
+			tableName := getTableNameWithSchema(td.Table.Schema, td.Table.Name, targetSchema)
+			sql := fmt.Sprintf("COMMENT ON COLUMN %s.%s IS %s;", tableName, ir.QuoteIdentifier(column.Name), quoteString(column.Comment))
+
+			context := &diffContext{
+				Type:                DiffTypeTableColumnComment,
+				Operation:           DiffOperationCreate,
+				Path:                fmt.Sprintf("%s.%s.%s", td.Table.Schema, td.Table.Name, column.Name),
+				Source:              column,
+				CanRunInTransaction: true,
+			}
+			collector.collect(context, sql)
+		}
+	}
+
 	// Modify existing columns - already sorted by the Diff operation
 	for _, ColumnDiff := range td.ModifiedColumns {
 		// Generate column modification statements and collect as a single step

testdata/diff/comment/mixed_comments/diff.sql

@@ -12,6 +12,10 @@ COMMENT ON COLUMN categories.created_at IS 'Category creation timestamp';
 
 COMMENT ON INDEX idx_categories_parent IS 'Index for hierarchical category queries';
 
+ALTER TABLE posts ADD COLUMN views integer DEFAULT 0;
+
+COMMENT ON COLUMN posts.views IS 'Number of post views';
+
 COMMENT ON TABLE posts IS 'Blog posts and articles';
 
 COMMENT ON COLUMN posts.id IS 'Unique post identifier';

testdata/diff/comment/mixed_comments/new.sql

@@ -3,14 +3,16 @@ CREATE TABLE posts (
     title VARCHAR(200) NOT NULL,
     content TEXT,
     author_id INTEGER NOT NULL,
-    published_at TIMESTAMP
+    published_at TIMESTAMP,
+    views INTEGER DEFAULT 0
 );
 COMMENT ON TABLE posts IS 'Blog posts and articles';
 COMMENT ON COLUMN posts.id IS 'Unique post identifier';
 COMMENT ON COLUMN posts.title IS 'Post title, max 200 characters';
 COMMENT ON COLUMN posts.content IS 'Post body in markdown format';
 COMMENT ON COLUMN posts.author_id IS 'Foreign key to users table';
 COMMENT ON COLUMN posts.published_at IS 'Publication timestamp, NULL for drafts';
+COMMENT ON COLUMN posts.views IS 'Number of post views';
 
 CREATE INDEX idx_posts_author ON posts (author_id);
 COMMENT ON INDEX idx_posts_author IS 'Index for finding posts by author';

testdata/diff/comment/mixed_comments/plan.json

@@ -50,6 +50,18 @@
           "operation": "alter",
           "path": "public.categories.idx_categories_parent"
         },
+        {
+          "sql": "ALTER TABLE posts ADD COLUMN views integer DEFAULT 0;",
+          "type": "table.column",
+          "operation": "create",
+          "path": "public.posts.views"
+        },
+        {
+          "sql": "COMMENT ON COLUMN posts.views IS 'Number of post views';",
+          "type": "table.column.comment",
+          "operation": "create",
+          "path": "public.posts.views"
+        },
         {
           "sql": "COMMENT ON TABLE posts IS 'Blog posts and articles';",
           "type": "table.comment",

testdata/diff/comment/mixed_comments/plan.sql

@@ -12,6 +12,10 @@ COMMENT ON COLUMN categories.created_at IS 'Category creation timestamp';
 
 COMMENT ON INDEX idx_categories_parent IS 'Index for hierarchical category queries';
 
+ALTER TABLE posts ADD COLUMN views integer DEFAULT 0;
+
+COMMENT ON COLUMN posts.views IS 'Number of post views';
+
 COMMENT ON TABLE posts IS 'Blog posts and articles';
 
 COMMENT ON COLUMN posts.id IS 'Unique post identifier';

testdata/diff/comment/mixed_comments/plan.txt

@@ -13,11 +13,13 @@ Tables:
     ~ categories (comment)
     ~ idx_categories_parent (index.comment)
   ~ posts
+    + views (column)
     ~ author_id (column.comment)
     ~ content (column.comment)
     ~ id (column.comment)
     ~ published_at (column.comment)
     ~ title (column.comment)
+    + views (column.comment)
     ~ posts (comment)
     ~ idx_posts_author (index.comment)
     ~ idx_posts_published (index.comment)
@@ -39,6 +41,10 @@ COMMENT ON COLUMN categories.created_at IS 'Category creation timestamp';
 
 COMMENT ON INDEX idx_categories_parent IS 'Index for hierarchical category queries';
 
+ALTER TABLE posts ADD COLUMN views integer DEFAULT 0;
+
+COMMENT ON COLUMN posts.views IS 'Number of post views';
+
 COMMENT ON TABLE posts IS 'Blog posts and articles';
 
 COMMENT ON COLUMN posts.id IS 'Unique post identifier';