I have a very large Perl hash has which contains ~600M entries (integer values). I was wondering if there is a limit for the number of entries in a hash. Also given this hash is so big, it requires a lot of memory and time to load. Does anyone have a suggestion for looking up data in a faster way? Would it be faster to store the data in an array/ hash? 

The goal of the project is to find if the value is present in a list or not (and then downstream analysis)? Does anything have a suggestion for quick search in Perl? 

--Diviya