Mysql range check instead of index usage on inner join

Ok, elementary problem. I owe myself a beer. The system I'm recently tunning is not a system I've developted - I've been assigned to it by my management to improve performance (originall team doesn't have knowledge on this topic).

After fee weeks of improving SQL queries, indexes, number of sql queries that are beeing executed by application I didn't check one of the most important things in this case !!

COLUMN TYPES ARE DIFFERENT !

Developer who have written than kind of code should get quite a big TALK.

Thanks for help !

I had the same problem with a different cause. I was joining a large table, and the ON clause used OR to compare the primary key (ii.itemid) to two different columns:

SELECT *
FROM share_detail sd
JOIN box_view bv ON sd.container_id = bv.id
JOIN boxes b ON b.id = bv.shared_id
JOIN item_index ii ON ii.itemid = bv.shared_id OR b.parent_itemid = ii.itemid;

Fortunately, it turned out the parent_itemid comparison was redundant, so I was able to remove it. Now the index is being used as expected. Otherwise, I was going to try splitting the item_index join into two separate joins.