MDL-86601 core_task: Add index for scheduled task lastruntime

public/lib/db/install.xml

@@ -3501,6 +3501,7 @@
       </KEYS>
       <INDEXES>
         <INDEX NAME="classname_uniq" UNIQUE="true" FIELDS="classname"/>
+        <INDEX NAME="lastruntime_nextruntime" UNIQUE="false" FIELDS="lastruntime, nextruntime"/>
       </INDEXES>
     </TABLE>
     <TABLE NAME="task_adhoc" COMMENT="List of adhoc tasks waiting to run.">

public/lib/db/upgrade.php

@@ -1684,5 +1684,19 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2026013000.01);
     }
 
+    if ($oldversion < 2026013000.02) {
+        // Define index lastruntime_nextruntime (not unique) to be added to task_scheduled.
+        $table = new xmldb_table('task_scheduled');
+        $index = new xmldb_index('lastruntime_nextruntime', XMLDB_INDEX_NOTUNIQUE, ['lastruntime', 'nextruntime']);
+
+        // Conditionally launch add index lastruntime_nextruntime.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2026013000.02);
+    }
+
     return true;
 }

public/version.php

@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2026013000.01;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2026013000.02;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.
 $release  = '5.2dev (Build: 20260130)';    // Human-friendly version name