Add a comment for CI_DB_sqlite3_result::num_rows()
diff --git a/system/database/drivers/sqlite3/sqlite3_result.php b/system/database/drivers/sqlite3/sqlite3_result.php
index 7b1b450..c9876fe 100644
--- a/system/database/drivers/sqlite3/sqlite3_result.php
+++ b/system/database/drivers/sqlite3/sqlite3_result.php
@@ -49,6 +49,9 @@
 	 */
 	public function num_rows()
 	{
+		/* The SQLite3 driver doesn't have a graceful way to do this,
+		 * so we'll have to do it on our own.
+		 */
 		return is_int($this->num_rows)
 			? $this->num_rows
 			: $this->num_rows = count($this->result_array());