Force index with active record find
A small useful tip:
Mysql’s query planner occasionally has trouble picking the right index. I’ve found that normally if you try variations long enough, eventually you find a way to do the right thing. Recently however I ran into one I couldn’t coax.
No big deal you say, after all, that’s what find_by_sql is for no? Only problem is, the query in question was inside a with_scope block, and I really didn’t want to have to find and hardcode sql finders for any variations used by callers. Thankfully, the :from option on find can rescue us: just go ahead and include the force index clause. It’s slightly gross imho, but it works, and might save you some manual sql building.
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