Php Cron processing

Dear All,
I have an application where it receive data from gps devices and write into the db. What I write will be raw data? So now I need to process the data. What I plan to do is that run a script every minute to check those unprocessed gps data to show which location,geo fence the gps data was in, generate alerts etc. The problem I am scared when I read raw data from the table at the same time a lot more data is bring written into the same table. Will there be any resource problem or locking problem? Why I never do it at the receing end the processing is because is heavy on query processing.