Add indexes to lotw_users table

Introduces migration 208 to add indexes on 'callsign' and 'lastupload' columns in the lotw_users table for improved query performance. Updates migration version to 208.

application/config/migration.php

@@ -22,7 +22,7 @@ $config['migration_enabled'] = TRUE;
 |
 */
 
-$config['migration_version'] = 207;
+$config['migration_version'] = 208;
 
 /*
 |--------------------------------------------------------------------------

application/migrations/208_add_indexes_lotw_users.php

@@ -0,0 +1,38 @@
+<?php
+defined('BASEPATH') or exit('No direct script access allowed');
+
+class Migration_add_indexes_lotw_users extends CI_Migration
+{
+    public function up()
+    {
+        if ($this->db->table_exists('lotw_users')) {
+            // add an index on callsign if no index exists on that column
+            $callsignIndex = $this->db->query("SHOW INDEX FROM lotw_users WHERE Column_name = 'callsign'");
+            if ($callsignIndex->num_rows() == 0) {
+                $this->db->query("ALTER TABLE lotw_users ADD INDEX `callsign` (`callsign`)");
+            }
+
+            // add an index on lastupload if it doesn't exist
+            $lastuploadIndex = $this->db->query("SHOW INDEX FROM lotw_users WHERE Column_name = 'lastupload'");
+            if ($lastuploadIndex->num_rows() == 0) {
+                $this->db->query("ALTER TABLE lotw_users ADD INDEX `lastupload` (`lastupload`)");
+            }
+        }
+    }
+
+    public function down()
+    {
+        if ($this->db->table_exists('lotw_users')) {
+            // drop the indexes we might have created (only if the index name matches)
+            $li = $this->db->query("SHOW INDEX FROM lotw_users WHERE Key_name = 'lastupload'");
+            if ($li->num_rows() > 0) {
+                $this->db->query("ALTER TABLE lotw_users DROP INDEX `lastupload`");
+            }
+
+            $ci = $this->db->query("SHOW INDEX FROM lotw_users WHERE Key_name = 'callsign'");
+            if ($ci->num_rows() > 0) {
+                $this->db->query("ALTER TABLE lotw_users DROP INDEX `callsign`");
+            }
+        }
+    }
+}