I had this on Magento 2.3.3 for a "custom stock" module that was running loops to grab data for a product and its child configurable products. As Magento is written in a modular way, asking a subcomponent for data can involve a database lookup so it is really slow to use and painful to debug.
Anyway, it was running 29000 database queries as it was repeatedly using an "in" clause of 1 item across hundreds of queries, instead of 1 query with hundreds of items in the "in" clause.
I replaced them with 1 query that fetched all it needed instead of the 29000 queries (and 8000+ which were duplicates).
Anyway, it was running 29000 database queries as it was repeatedly using an "in" clause of 1 item across hundreds of queries, instead of 1 query with hundreds of items in the "in" clause.
I replaced them with 1 query that fetched all it needed instead of the 29000 queries (and 8000+ which were duplicates).
Terrible code.