From bbea936991740a28bd203d40f2caa1cb321eb9cf Mon Sep 17 00:00:00 2001
From: Tim Hunt <T.J.Hunt@open.ac.uk>
Date: Fri, 8 Aug 2014 13:56:23 +0100
Subject: [PATCH] MDL-45642 questions: add required index to question_attempts.

It is important to be able to tell which behaviours are in use, and
without this index, it requires a complete scan of this table, which can
be very big, to verify that a behaviour is unused.
---
 lib/db/install.xml |  3 ++-
 lib/db/upgrade.php | 15 +++++++++++++++
 version.php        |  2 +-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/lib/db/install.xml b/lib/db/install.xml
index ac9693e5b70..21490f84781 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="lib/db" VERSION="20140627" COMMENT="XMLDB file for core Moodle tables"
+<XMLDB PATH="lib/db" VERSION="20140808" COMMENT="XMLDB file for core Moodle tables"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
 >
@@ -1323,6 +1323,7 @@
       </KEYS>
       <INDEXES>
         <INDEX NAME="questionusageid-slot" UNIQUE="true" FIELDS="questionusageid, slot"/>
+        <INDEX NAME="behaviour" UNIQUE="false" FIELDS="behaviour" COMMENT="Required because we need to be able to determine efficiently which behaviours are in use."/>
       </INDEXES>
     </TABLE>
     <TABLE NAME="question_attempt_steps" COMMENT="Stores one step in in a question attempt. As well as the data here, the step will have some data in the question_attempt_step_data table.">
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 5d88ee49a47..4a9c741a1c2 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -3719,5 +3719,20 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2014072400.01);
     }
 
+    if ($oldversion < 2014080801.00) {
+
+        // Define index behaviour (not unique) to be added to question_attempts.
+        $table = new xmldb_table('question_attempts');
+        $index = new xmldb_index('behaviour', XMLDB_INDEX_NOTUNIQUE, array('behaviour'));
+
+        // Conditionally launch add index behaviour.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2014080801.00);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index 81f07c94397..8c92a7a3e36 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2014080700.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2014080801.00;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.