> When purgeInternal is invoked I delete all rows which have a column in the range "Infinispan:expiration0000000000000000" to "Infinispan:expiration0paddednowtimestamp".

Is this efficient from a Cassandra perspective?  Would this not involve a lot of String comparisons?

Cassandra stores columns adjacently according to a predefined user-defined algorithm. Since all columns are going to be ordered by ascending expiration this operation is quite quick.

Tristan