char based partitioning

Hi,
I have huge table like 20mln records in 50 columns.
I want to partition this table by char field.

mysql> describe hist;
±-----------±---------±-----±----±--------±------+
| Field | Type | Null | Key | Default | Extra |
±-----------±---------±-----±----±--------±------+
| SHOP | char(20) | YES | MUL | NULL | |

So i have 20 different shops and they are like Wexford, Waterford etc and want to have one partition per one shop. Is it possible to do ? I saw few examples with ASCII() function but it takes only first character from string so 2 abovementioned shops will be in same partition what i want to avoid. Is there any function which make a integer hash from char field ? even taking 2 first characters from shop name would help me. regards

Michal

are you talking about mysql’s substring?

http://dev.mysql.com/doc/refman/5.0/en/string-functions.html