MySQL “IN” operator performance on (large?) number of values

Question

I have been experimenting with Redis and MongoDB lately and it would seem that there are often cases where you would store an array of id\'s in either Mongo

Answer 1

Using IN with a large parameter set on a large list of records will in fact be slow.

In the case that I solved recently I had two where clauses, one with 2,50 parameters and the other with 3,500 parameters, querying a table of 40 Million records.

My query took 5 minutes using the standard WHERE IN. By instead using a subquery for the IN statement (putting the parameters in their own indexed table), I got the query down to TWO seconds.

Worked for both MySQL and Oracle in my experience.