db: schema upgrade 1: add titles.is_deleted column

DB.go

@@ -69,9 +69,10 @@ func (this *WikiDB) assertSchema() error {
 
 	log.Printf("Found DB version %d\n", currentSchema)
 
-	// Schema 0 ==> Schema 1
+	//
 
 	if currentSchema == 0 {
+		// Schema 0 ==> Schema 1
 		log.Println("Upgrading to DB version 1")
 
 		err := this.multiTx(
@@ -96,6 +97,23 @@ func (this *WikiDB) assertSchema() error {
 		currentSchema = 1
 	}
 
+	//
+
+	if currentSchema == 1 {
+		log.Println("Upgrading to DB version 2")
+
+		err := this.multiTx(
+			`ALTER TABLE titles ADD COLUMN is_deleted INTEGER DEFAULT 0;`,
+			`INSERT INTO schema (id) VALUES (2);`,
+		)
+		if err != nil {
+			return err
+		}
+		currentSchema = 1
+	}
+
+	//
+
 	return nil
 }