From 2c6b80f4003ec67e52baa5f546ee3ceee0827e31 Mon Sep 17 00:00:00 2001
From: Frederic Massart <fred@moodle.com>
Date: Fri, 27 Jun 2014 09:38:38 +0100
Subject: [PATCH] MDL-48069 files: Switch the field order of index on
 mdl_files_reference

To improve performance of file_storage::search_references
---
 lib/db/install.xml |  6 +++---
 lib/db/upgrade.php | 18 ++++++++++++++++++
 version.php        |  2 +-
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/lib/db/install.xml b/lib/db/install.xml
index a3a89fc33bb..0d0b9bc12e5 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="20140324" COMMENT="XMLDB file for core Moodle tables"
+<XMLDB PATH="lib/db" VERSION="20150102" COMMENT="XMLDB file for core Moodle tables"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
 >
@@ -2359,7 +2359,7 @@
         <KEY NAME="repositoryid" TYPE="foreign" FIELDS="repositoryid" REFTABLE="repository_instances" REFFIELDS="id"/>
       </KEYS>
       <INDEXES>
-        <INDEX NAME="uq_external_file" UNIQUE="true" FIELDS="repositoryid, referencehash" COMMENT="The combination of repositoryid and reference field is supposed to be a unique identification of an external file. Because the reference is a TEXT field, we can't use to compose the index. So we use the referencehash instead and the file API is responsible to keep it up-to-date"/>
+        <INDEX NAME="uq_external_file" UNIQUE="true" FIELDS="referencehash, repositoryid" COMMENT="The combination of repositoryid and reference field is supposed to be a unique identification of an external file. Because the reference is a TEXT field, we can't use to compose the index. So we use the referencehash instead and the file API is responsible to keep it up-to-date"/>
       </INDEXES>
     </TABLE>
     <TABLE NAME="repository" COMMENT="This table contains one entry for every configured external repository instance.">
@@ -3034,4 +3034,4 @@
       </INDEXES>
     </TABLE>
   </TABLES>
-</XMLDB>
+</XMLDB>
\ No newline at end of file
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 8f6d715b381..b8b246b5f0a 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -3714,5 +3714,23 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2014051202.11);
     }
 
+    // Switch the order of the fields in the files_reference index, to improve the performance of search_references.
+    if ($oldversion < 2014051203.08) {
+        $table = new xmldb_table('files_reference');
+        $index = new xmldb_index('uq_external_file', XMLDB_INDEX_UNIQUE, array('repositoryid', 'referencehash'));
+        if ($dbman->index_exists($table, $index)) {
+            $dbman->drop_index($table, $index);
+        }
+        upgrade_main_savepoint(true, 2014051203.08);
+    }
+    if ($oldversion < 2014051203.09) {
+        $table = new xmldb_table('files_reference');
+        $index = new xmldb_index('uq_external_file', XMLDB_INDEX_UNIQUE, array('referencehash', 'repositoryid'));
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+        upgrade_main_savepoint(true, 2014051203.09);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index 2b25c817f33..2aa893c4dfe 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2014051203.07;              // 20140512      = branching date YYYYMMDD - do not modify!
+$version  = 2014051203.09;              // 20140512      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.