How COBOL FLAT files(Index,Sequential) are very secure for huge data?If not, How will you migrate with any Database with Frond end COBOL?

How COBOL FLAT files(Index,Sequential) are very secure for huge data?If not, How will you migrate with any Database with Frond end COBOL?

Well if you are using flat file you have advantage as well as disadvantages.
Advantage -It is Secure Physically edited.
Disadvantage - Logically speaking performance is slow difficult to find the particular record.