[Zope] Finding a match in a large dataset - btrees?

[Cameron Beattie]

Thanks for the many replies. I apologise for the original message which was 
obviously very unclear - I will try to correct that.

Basically I want to match a telephone number to a rate table. Assume the 
following rate table:
Telephone code    Rate
649                1
6421                2
6422                2.5
64                 1.5

The following table sets out the appropriate rate to return for a given 
telephone number
Dialled number    Returned rate
649123                     1
643123                    1.5
6421111                    2
64221                      2.5

Things to note:
If there is no match the right-most digit is removed until there is a match 
e.g. 643123 matches to 64
The length of the "dialled number" is not consistent e.g. 649123 vs 64221
The length of the "telephone code" is not consistent e.g. 64 vs 6422

I want to do this frequently and at low cost i.e. ideally in memory. Perhaps 
the best way is to write a procedure in MySQL however I am interested in any 
python-based alternatives.

Regards

Cameron