Custom Input Split

[Rakhi Khatwani]

Hi,
     I have a table with N records,
     now i want to run a map reduce job with 4 maps and 0 reduces.
     is there a way i can create my own custom input split so that i can
send 'n' records to each map??
    if there is a way, can i have a sample code snippet to gain better
understanding?

Thanks
Raakhi.