From 9b3646417e8f64d42df05bfc3f056fde57cf2787 Mon Sep 17 00:00:00 2001
From: sam marshall <s.marshall@open.ac.uk>
Date: Thu, 14 May 2020 16:15:46 +0100
Subject: [PATCH] MDL-68726 Search: Stop Solr 'optimize' behaviour

The optimize feature in Solr is usually considered harmful, especially
prior to Solr 7.5.

This change simply removes the optimize implementation from the Solr
engine.
---
 search/classes/engine.php             | 2 ++
 search/engine/solr/classes/engine.php | 9 ---------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/search/classes/engine.php b/search/classes/engine.php
index 55c59637aa68c..5854c025a721f 100644
--- a/search/classes/engine.php
+++ b/search/classes/engine.php
@@ -394,6 +394,8 @@ public function area_index_complete($searcharea, $numdocs = 0, $fullindex = fals
      */
     public function optimize() {
         // Nothing by default.
+        mtrace('The ' . get_string('pluginname', $this->get_plugin_name()) .
+                ' search engine does not require automatic optimization.');
     }
 
     /**
diff --git a/search/engine/solr/classes/engine.php b/search/engine/solr/classes/engine.php
index a20d79e6b3ffb..0d433ab1152a6 100644
--- a/search/engine/solr/classes/engine.php
+++ b/search/engine/solr/classes/engine.php
@@ -1203,15 +1203,6 @@ public function file_indexing_enabled() {
         return (bool)$this->config->fileindexing;
     }
 
-    /**
-     * Defragments the index.
-     *
-     * @return void
-     */
-    public function optimize() {
-        $this->get_search_client()->optimize(1, true, false);
-    }
-
     /**
      * Deletes the specified document.
      *