MDL-34933 core_message: Adding index to improve database access on message_working table.

lib/db/install.xml

@@ -2363,6 +2363,9 @@
       <KEYS>
         <KEY NAME="primary" TYPE="primary" FIELDS="id" COMMENT="primary key of the table, please edit me"/>
       </KEYS>
+      <INDEXES>
+        <INDEX NAME="unreadmessageid_idx" UNIQUE="false" FIELDS="unreadmessageid" COMMENT="Index on unreadmessage id"/>
+      </INDEXES>
     </TABLE>
     <TABLE NAME="files" COMMENT="description of files, content is stored in sha1 file pool" PREVIOUS="message_working" NEXT="files_reference">
       <FIELDS>

lib/db/upgrade.php

@@ -1687,5 +1687,19 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2012120303.02);
     }
 
+    if ($oldversion < 2012120303.06) {
+        // Adding index to unreadmessageid field of message_working table (MDL-34933)
+        $table = new xmldb_table('message_working');
+        $index = new xmldb_index('unreadmessageid_idx', XMLDB_INDEX_NOTUNIQUE, array('unreadmessageid'));
+
+        // Conditionally launch add index unreadmessageid
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+        
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2012120303.06);
+    }
+
     return true;
 }

version.php

@@ -30,7 +30,7 @@
 defined('MOODLE_INTERNAL') || die();
 
 
-$version  = 2012120303.05;              // 20121203      = branching date YYYYMMDD - do not modify!
+$version  = 2012120303.06;              // 20121203      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches
                                         //           .XX = incremental changes