Persistent data structures

Abstract

All programs that we have written thus far suffer from a serious flaw: we cannot terminate them without losing all our data. We developed refined structures to allocate memory for our data elegantly and efficiently. But as soon as the program terminates – or in the event of a power failure – we lose all data. In the main memory of our Computer, all data are temporary; they can only be accessed by a running program and require the power supply of the Computer. For this reason practically all Computers are equipped with storage media that can retain data even without a continuous power supply. We call these hard disks or diskettes – collectively background storage. We must store our data on such background storage to allow them to survive the end of the program. We call such nontemporary data persistent.