QueuedJob query using 'Implementation' column without index

[brettt89]

The SiteTree extension, when calling 'default records' function, queries the QueuedJobDescriptor table for a ContentReviewJob. However it is doing so using the Implementation column which does not have any index associated.

https://github.com/silverstripe/silverstripe-contentreview/blob/4/src/Extensions/SiteTreeContentReview.php#L666

As the QueuedJobDescsriptor.Implementation column is a varchar(255), it is having to do a full-scan on the table when searching, this takes quite a while to perform and gets exponentially worse with the more records in this table.

E.g. A QueuedJobDescriptor table with 180k records takes over 1 minute to run this single query.

[Cheddam]

Thanks for raising this @brettt89! Unfortunately this isn't really an issue with the Content Review module, and it's certainly not solvable by this module (short of applying an extension to the QueuedJobDescriptor model to patch in an index, which definitely feels like the wrong approach.)

Since an issue addressing this has also been raised about this on the Queued Jobs module, I think we'll close this one out in favour of tackling the resolution there.