From 82b7ad70b1772e3f57d25ca6db3810794b6bc455 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Mudr=C3=A1k?= <david@moodle.com>
Date: Mon, 18 Jun 2018 16:53:03 +0200
Subject: [PATCH] MDL-62621 comments: Add missing indexes on comments table

The composite index over the fields contextid, commentarea and itemid
helps the comments API to load all comments for the given area
effectively.

The index over the userid field helps the privacy API to load all
comments by the given user.
---
 lib/db/install.xml |  6 +++++-
 lib/db/upgrade.php | 21 +++++++++++++++++++++
 version.php        |  2 +-
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/lib/db/install.xml b/lib/db/install.xml
index b9b900372d2..8e4dd6215f0 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="20180403" COMMENT="XMLDB file for core Moodle tables"
+<XMLDB PATH="lib/db" VERSION="20180618" COMMENT="XMLDB file for core Moodle tables"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
 >
@@ -2638,7 +2638,11 @@
       </FIELDS>
       <KEYS>
         <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
+        <KEY NAME="fk_user" TYPE="foreign" FIELDS="userid" REFTABLE="user" REFFIELDS="id"/>
       </KEYS>
+      <INDEXES>
+        <INDEX NAME="ix_concomitem" UNIQUE="false" FIELDS="contextid, commentarea, itemid" COMMENT="Allows the comments API to load comments for a particular area effectively."/>
+      </INDEXES>
     </TABLE>
     <TABLE NAME="external_services" COMMENT="built in and custom external services">
       <FIELDS>
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index cc7edbd15a3..7ddc87689a3 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -2233,5 +2233,26 @@ function xmldb_main_upgrade($oldversion) {
     // Automatically generated Moodle v3.5.0 release upgrade line.
     // Put any upgrade step following this.
 
+    if ($oldversion < 2018062800.01) {
+        // Add foreign key fk_user to the comments table.
+        $table = new xmldb_table('comments');
+        $key = new xmldb_key('fk_user', XMLDB_KEY_FOREIGN, array('userid'), 'user', array('id'));
+        $dbman->add_key($table, $key);
+
+        upgrade_main_savepoint(true, 2018062800.01);
+    }
+
+    if ($oldversion < 2018062800.02) {
+        // Add composite index ix_concomitem to the table comments.
+        $table = new xmldb_table('comments');
+        $index = new xmldb_index('ix_concomitem', XMLDB_INDEX_NOTUNIQUE, array('contextid', 'commentarea', 'itemid'));
+
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        upgrade_main_savepoint(true, 2018062800.02);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index d6966f378ef..be6a9625b9e 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2018062800.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2018062800.02;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.