Hi monks, I am new to perl and currently I writing a perl script for manipulating large data with hel of lookup in hash. I have lookup file with (created from database) phone-number,group-id,start-dat,end-dat values , this file will have 100k records and i get have a file with phone number(both calling and caled number ) and call time . so i have to look up the calling number and called number in the look up file to get the group id and start time and end time. I thought of pushing all 100k records to hash from the file and the do the comparison, but I am stucked at the point, which value should be given as key value.what i understood from tutorial that key value should be unique, but in my case first I thought of putting phone number as key, but there is always a chance the phone number can be blong to differnt group for different startdate and end date.I cannot overwrite the old data also. I have mainly two concerns 1>100k records fetching to a file and push that data to hash at the begginning of the script is better or directly accesing database and push data to hash is better approach. 2>how can make unique key with these combination or is ther any way out of it? plz hel me... thax in advance