Add index on customcert_issues table (#537)

db/install.xml

@@ -54,6 +54,9 @@
         <KEY NAME="primary" TYPE="primary" FIELDS="id" COMMENT="Primary key for customcert_issues"/>
         <KEY NAME="customcert" TYPE="foreign" FIELDS="customcertid" REFTABLE="customcert" REFFIELDS="id"/>
       </KEYS>
+      <INDEXES>
+        <INDEX NAME="userid-customcertid" UNIQUE="true" FIELDS="userid, customcertid"/>
+      </INDEXES>
     </TABLE>
     <TABLE NAME="customcert_pages" COMMENT="Stores each page of a custom cert">
       <FIELDS>

db/upgrade.php

@@ -200,5 +200,18 @@ function xmldb_customcert_upgrade($oldversion) {
         upgrade_mod_savepoint(true, 2022041903, 'customcert'); // Replace with the actual version number.
     }
 
+    if ($oldversion < 2022041906) {
+        // Define index to be added to customcert_issues.
+        $table = new xmldb_table('customcert_issues');
+        $index = new xmldb_index('userid-customcertid', XMLDB_INDEX_UNIQUE, ['userid', 'customcertid']);
+
+        // Conditionally launch add index.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        upgrade_mod_savepoint(true, 2022041906, 'customcert'); // Replace with the actual version number.
+    }
+
     return true;
 }

version.php

@@ -24,7 +24,7 @@
 
 defined('MOODLE_INTERNAL') || die('Direct access to this script is forbidden.');
 
-$plugin->version   = 2022041905; // The current module version (Date: YYYYMMDDXX).
+$plugin->version   = 2022041906; // The current module version (Date: YYYYMMDDXX).
 $plugin->requires  = 2022041900; // Requires this Moodle version (4.0).
 $plugin->cron      = 0; // Period for cron to check this module (secs).
 $plugin->component = 'mod_customcert';