Create tag_id index for history table

astrid/src/com/todoroo/astrid/dao/Database.java

@@ -153,6 +153,13 @@ public class Database extends AbstractDatabase {
         append(')');
         database.execSQL(sql.toString());
         sql.setLength(0);
+
+        sql.append("CREATE INDEX IF NOT EXISTS hist_tag_id ON ").
+        append(History.TABLE).append('(').
+        append(History.TAG_ID.name).
+        append(')');
+        database.execSQL(sql.toString());
+        sql.setLength(0);
     }
 
     @Override