That's one way
I'd do it this way
1. install mysql server and configure innodb_buffer_pool_size to be 90% of system memory (i might use someone's server for this) :)
2. create a table with four fields (id - autoinc, unclean - varchar(256), trndate (datetime), seq nos (innodb table to make use of 1 above)
3. index id primary in one index, trndate in another
4. import into the database, throw everything into the unclean field
5. wait :)
6. run query to split for example update mytable set trndate = left(unclean,8), seqno = substr(unclean,9,255) - i've noticed the format is yyyymmdd - makes it easier, you'd have to confirm my statement since i just wrote it from memory
7. wait again
8. then do selects and export to text files - the index on the trndate should make it super fast
don't forget to put the indexes otherwise it will take forever to do the queries
just a suggestion... and in the end you'll have a nice neat table in case you want to do more perations on it. You can even back it up and zip it for storage!