[5.3] Smart Search: Improve Indexer::optimize()

[Hackwar]

Summary of Changes

This PR does several optimizations for the optimize step of the indexing in Smart Search. With the current order, the count of links to terms is not updated and terms are deleted before other orphaned data might be removed. At the same time it uses a different method to delete orphaned taxonomies. Running the normal Table::delete() operation on the nested set table class of the taxonomy table is VERY expensive and takes ages. This new code deletes all orphaned leaf nodes in one step, then rebuilds the tree and the path and then tries that again until there are no orphaned leaf nodes anymore. This is by far quicker than the old method.

Testing Instructions

Make sure that you have a sizeable Smart Search index. Go into the #__finder_links table and delete one or several rows. Now in the Index view of Smart Search click on Maintenance => Optimize.

Actual result BEFORE applying this Pull Request

Optimize step takes quite some time and doesn't necessarily delete orphaned terms.

Expected result AFTER applying this Pull Request

Optimize step is far quicker and deletes all orphaned terms.

Link to documentations

Please select:

• [ ] Documentation link for docs.joomla.org:

• [X] No documentation changes for docs.joomla.org needed

• [ ] Pull Request link for manual.joomla.org:

• [X] No documentation changes for manual.joomla.org needed

[richard67]

Will this PR fix issue #44470 ?

[Hackwar]

It should greatly improve the situation. I'm not going to guarantee anything, but it is worth a try.

[dautrich]

I have tested this item :white_check_mark: successfully on 253cf3d34c4803c54142eac101071f764b94cf53

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