diff --git a/classes/local.php b/classes/local.php
index 9b74d4b..94b9e6a 100644
--- a/classes/local.php
+++ b/classes/local.php
@@ -26,6 +26,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
+use core_text;
 use stored_file;
 
 /**
@@ -132,7 +133,13 @@ public static function get_optimised_src(\stored_file $file, $originalsrc, $opti
     public static function add_url_path_to_queue($path) {
         global $DB;
 
-        $existing = $DB->get_record('filter_imageopt', ['urlpath' => $path]);
+        $existing = $DB->get_record_select(
+            'filter_imageopt',
+            $DB->sql_compare_text('urlpath', core_text::strlen($path)) . '= :path',
+            ['path' => $path],
+            '*',
+            IGNORE_MULTIPLE // It's very unlikely but there is a possible race condition where multiple records exist.
+        );
         if ($existing) {
             return $existing->id;
         }
@@ -164,7 +171,11 @@ public static function get_url_path_by_id($id) {
     public static function delete_queue_item_by_path($urlpath) {
         global $DB;
 
-        $DB->delete_records('filter_imageopt', ['urlpath' => $urlpath]);
+        $DB->delete_records_select(
+            'filter_imageopt',
+            $DB->sql_compare_text('urlpath', core_text::strlen($urlpath)) . '= :path',
+            ['path' => $urlpath]
+        );
     }
 
     /**
diff --git a/classes/task/expirequeue.php b/classes/task/expirequeue.php
new file mode 100644
index 0000000..13e50b5
--- /dev/null
+++ b/classes/task/expirequeue.php
@@ -0,0 +1,47 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * @package filter_imageopt
+ * @author Andrew Hancox <andrewdchancox@googlemail.com>
+ * @author Open Source Learning <enquiries@opensourcelearning.co.uk>
+ * @link https://opensourcelearning.co.uk
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @copyright 2024, Andrew Hancox
+ */
+
+namespace filter_imageopt\task;
+
+defined('MOODLE_INTERNAL') || die();
+
+class expirequeue extends \core\task\scheduled_task {
+    /**
+     * @return string
+     */
+    public function get_name() {
+        return get_string('expirequeuetask', 'filter_imageopt');
+    }
+
+    public function execute() {
+        global $DB;
+
+        $DB->delete_records_select(
+            'filter_imageopt',
+            'timecreated < :time',
+            ['time' => time() - YEARSECS]
+        );
+    }
+}
diff --git a/db/install.xml b/db/install.xml
index 65c2276..8760fb3 100644
--- a/db/install.xml
+++ b/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="filter/imageopt/db" VERSION="20180618" COMMENT="XMLDB file for Moodle filter/imageopt"
+<XMLDB PATH="filter/imageopt/db" VERSION="20240131" COMMENT="XMLDB file for Moodle filter/imageopt"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../../lib/xmldb/xmldb.xsd"
 >
@@ -7,16 +7,13 @@
     <TABLE NAME="filter_imageopt" COMMENT="Table for tracking image url processing.">
       <FIELDS>
         <FIELD NAME="id" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="true"/>
-        <FIELD NAME="urlpath" TYPE="char" LENGTH="255" NOTNULL="true" SEQUENCE="false"/>
+        <FIELD NAME="urlpath" TYPE="text" NOTNULL="true" SEQUENCE="false"/>
         <FIELD NAME="timecreated" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false"/>
         <FIELD NAME="timeprocessed" TYPE="int" LENGTH="10" NOTNULL="false" SEQUENCE="false"/>
       </FIELDS>
       <KEYS>
         <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
       </KEYS>
-      <INDEXES>
-        <INDEX NAME="urlpath" UNIQUE="true" FIELDS="urlpath"/>
-      </INDEXES>
     </TABLE>
   </TABLES>
-</XMLDB>
\ No newline at end of file
+</XMLDB>
diff --git a/db/tasks.php b/db/tasks.php
new file mode 100755
index 0000000..738fbbe
--- /dev/null
+++ b/db/tasks.php
@@ -0,0 +1,40 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * @package filter_imageopt
+ * @author Andrew Hancox <andrewdchancox@googlemail.com>
+ * @author Open Source Learning <enquiries@opensourcelearning.co.uk>
+ * @link https://opensourcelearning.co.uk
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @copyright 2024, Andrew Hancox
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+$tasks = [
+        [
+                'classname' => '\filter_imageopt\task\expirequeue',
+                'blocking'  => 0,
+                'minute'    => '0',
+                'hour'      => '0',
+                'day'       => '*',
+                'month'     => '*',
+                'dayofweek' => '*',
+                'disabled'  => 0
+        ],
+];
+
diff --git a/db/upgrade.php b/db/upgrade.php
index 729f274..8d66ded 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -60,6 +60,25 @@ function xmldb_filter_imageopt_upgrade($oldversion) {
         // Imageopt savepoint reached.
         upgrade_plugin_savepoint(true, 2018061803, 'filter', 'imageopt');
     }
+    if ($oldversion < 2024013100) {
+
+        // Define index urlpath (unique) to be dropped form filter_imageopt.
+        $table = new xmldb_table('filter_imageopt');
+        $index = new xmldb_index('urlpath', XMLDB_INDEX_UNIQUE, ['urlpath']);
+
+        // Conditionally launch drop index urlpath.
+        if ($dbman->index_exists($table, $index)) {
+            $dbman->drop_index($table, $index);
+        }
+
+        $field = new xmldb_field('urlpath', XMLDB_TYPE_TEXT, null, null, XMLDB_NOTNULL, null, null, 'id');
+
+        // Launch change of type for field urlpath.
+        $dbman->change_field_type($table, $field);
+
+        // Imageopt savepoint reached.
+        upgrade_plugin_savepoint(true, 2024013100, 'filter', 'imageopt');
+    }
 
     return true;
 }
diff --git a/lang/en/filter_imageopt.php b/lang/en/filter_imageopt.php
index f17db77..3562ac2 100644
--- a/lang/en/filter_imageopt.php
+++ b/lang/en/filter_imageopt.php
@@ -21,6 +21,7 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 $string['cachedef_public_files'] = 'Cache of public file contenthashes';
+$string['expirequeuetask'] = 'Expire queued images';
 $string['filtername'] = 'Image optimiser';
 $string['maxwidth'] = 'Maximum image width';
 $string['maxwidthdesc'] = 'Maximum image width in pixels';
diff --git a/tests/filter_test.php b/tests/filter_test.php
index f1ce1cb..6173883 100644
--- a/tests/filter_test.php
+++ b/tests/filter_test.php
@@ -27,6 +27,7 @@
 defined('MOODLE_INTERNAL') || die();
 
 use context;
+use core_text;
 use moodle_url;
 use stored_file;
 use phpunit_util;
@@ -121,7 +122,11 @@ public function test_image_opt_url() {
 
         $url = phpunit_util::call_internal_method($filter, 'image_opt_url', [$file, $originalurl], get_class($filter));
 
-        $row = $DB->get_record('filter_imageopt', ['urlpath' => 'pluginfile.php/somefile.jpg']);
+        $path = "pluginfile.php/somefile.jpg";
+        $row = $DB->get_record_select(
+            'filter_imageopt',
+            $DB->sql_compare_text('urlpath', core_text::strlen($path)) . "= '{$path}'"
+        );
         $urlpathid = $row->id;
 
         $expected = new moodle_url(
diff --git a/version.php b/version.php
index cd42b05..47b0d8c 100644
--- a/version.php
+++ b/version.php
@@ -22,7 +22,7 @@
  */
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2022020800;
+$plugin->version   = 2024013101;
 $plugin->requires  = 2011111500;
 $plugin->component = 'filter_imageopt';
 $plugin->maturity  = MATURITY_BETA;