On 25.02.2011 17:57, Nick Brown wrote: > Are the lookup, insertion, deletion, and sort costs of Hash objects > documented anywhere? I would be interested in average-case > and worst-case times... are they linear, logarithmic, exponential, etc. > in time? Are you familiar with hashing in general? If not, please have a look here: http://en.wikipedia.org/wiki/Hash_table#Performance_analysis http://en.wikipedia.org/wiki/Hash_function If you want true numbers you need to benchmark because all theory may fail you for particular data or access patterns. > Also, is there a way to 'tune' hashes so that they use underlying > algorithms which are faster at, say, look-ups over inserts or > vice-versa? That would be killer. You can't modify internal workings of the built in Hash class unless you start patching the C code. But of course you can create your own implementation for custom cases. Cheers robert -- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/