Hi,

My moodle platform contains very large courses (900 sections and 5000 modules on average). Course caching takes a while (several minutes and several thousand of database queries). On any course modification, the cache is rebuild.

I increase the values of MAX_MODINFO_CACHE_SIZE and CONTEXT_CACHE_MAX_SIZE to limit the amount of database queries:

// config.php

define('MAX_MODINFO_CACHE_SIZE', INF);

define('CONTEXT_CACHE_MAX_SIZE', INF);

But there is still costly repeated database queries on all pages, when I used section options :

$section_info->{option_name};

# ...

SELECT id,name,value FROM mdl_course_format_options WHERE courseid = '206' AND format = '...' AND sectionid = '2202'

SELECT id,name,value FROM mdl_course_format_options WHERE courseid = '206' AND format = '...' AND sectionid = '2207'

SELECT id,name,value FROM mdl_course_format_options WHERE courseid = '206' AND format = '...' AND sectionid = '2212'

SELECT id,name,value FROM mdl_course_format_options WHERE courseid = '206' AND format = '...' AND sectionid = '2216'

# ...

or when I want to get user-depended data :

get_fast_modinfo($course, $user);

How to improve the cache performance and how to limit the amount of repeated database queries?

My configuration :

• Moodle: 2.9 (Build: 20150511)
• Database: MariaDB Galera Cluster
• Cache stores: Memcached server for application and session caches