text partition key Bloom filters fp is 1 always, why?

[Anishek Agarwal <an...@gmail.com>]

Hello,

I have a text partition key for one of the CF. The cfstats on that table
seems to show that the bloom filter false positive ratio is always 1. Also
the bloom filter is using very less space.

Do bloom filters not work well with text partition keys ? I can assume this
as it can no way detect the length of the text and hence would have a very
high false positive.

The text partition key is combined using a long + "_" +
epoch_time_in_hours, would it be better if we have a composite partition
key of the (long, epoch_time_in_hours) rather than combining it as a text
key ?


Thanks
anishek