Improve performance of get_all_groups_of_choices

[aneno-m-e]

One of our clients is facing performance issues (504 Gateway Time-out) when using this plugin in certain courses.

We've identified the function get_all_groups_of_choices as a cause and rewrote it to minimise the number of database queries done in order to retrieve $groupids.

[dlmsr]

Hi @aneno-m-e, thanks for your contribution which is a real improvement. Is there a reason why you do not have the following query (note the WHERE clause):

  SELECT DISTINCT
    g.id
  FROM
    {ratingallocate_choices} c
    JOIN {ratingallocate_group_choices} gc ON gc.choiceid = c.id
    JOIN {groups} g ON gc.groupid = g.id
  WHERE
    c.ratingallocateid = ?
    AND c.usegroups = 1
    AND c.active = 1;

This is what I considered when reviewing get_all_groups_of_choices.

[aneno-m-e]

Hi @dlmsr

I had a look at the query and I believe the only reason we didn't include AND c.usegroups = 1 AND c.active = 1; was because we needed a fix asap and didn't get the opportunity to optimise the query as well as could be.

[dlmsr]

Ok, thanks. Then I am going with my version of the query :)