MDL-59438 calendar: Added a foreign key and an index

Added foreign key constraint to the event.subscriptionid column.
Also added index to the event.uuid column.

lib/db/install.xml

 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="lib/db" VERSION="20171026" COMMENT="XMLDB file for core Moodle tables"
+<XMLDB PATH="lib/db" VERSION="20171205" COMMENT="XMLDB file for core Moodle tables"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
 >
@@ -449,12 +449,14 @@
       <KEYS>
         <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
         <KEY NAME="categoryid" TYPE="foreign" FIELDS="categoryid" REFTABLE="course_categories" REFFIELDS="id"/>
+        <KEY NAME="subscriptionid" TYPE="foreign" FIELDS="subscriptionid" REFTABLE="event_subscriptions" REFFIELDS="id"/>
       </KEYS>
       <INDEXES>
         <INDEX NAME="courseid" UNIQUE="false" FIELDS="courseid"/>
         <INDEX NAME="userid" UNIQUE="false" FIELDS="userid"/>
         <INDEX NAME="timestart" UNIQUE="false" FIELDS="timestart"/>
         <INDEX NAME="timeduration" UNIQUE="false" FIELDS="timeduration"/>
+        <INDEX NAME="uuid" UNIQUE="false" FIELDS="uuid"/>
         <INDEX NAME="type-timesort" UNIQUE="false" FIELDS="type, timesort"/>
         <INDEX NAME="groupid-courseid-categoryid-visible-userid" UNIQUE="false" FIELDS="groupid, courseid, categoryid, visible, userid" COMMENT="used for calendar view"/>
       </INDEXES>
@@ -3760,4 +3762,4 @@
       </KEYS>
     </TABLE>
   </TABLES>
-</XMLDB>
+</XMLDB>
\ No newline at end of file

lib/db/upgrade.php

@@ -1837,5 +1837,27 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2017111300.02);
     }
 
+    if ($oldversion < 2017120100.01) {
+
+        // Define key subscriptionid (foreign) to be added to event.
+        $table = new xmldb_table('event');
+        $key = new xmldb_key('subscriptionid', XMLDB_KEY_FOREIGN, array('subscriptionid'), 'event_subscriptions', array('id'));
+
+        // Launch add key subscriptionid.
+        $dbman->add_key($table, $key);
+
+        // Define index uuid (not unique) to be added to event.
+        $table = new xmldb_table('event');
+        $index = new xmldb_index('uuid', XMLDB_INDEX_NOTUNIQUE, array('uuid'));
+
+        // Conditionally launch add index uuid.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2017120100.01);
+    }
+
     return true;
 }

version.php

@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2017120800.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2017120800.01;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.