Programming the Perl DBI

Summary of Flat-File Databases

The main benefit of using flat-file databases for data storage is that they can be fast to implement and fast to use on small and straightforward datasets, such as our megalithic database or a Unix password file.

The code to query, insert, delete, and update information in the database is also extremely simple, with the parsing code potentially shared among the operations. You have total control over the data file formats, so that there are no situations outside your control in which the file format or access API changes. The files are also easy to read in standard text editors (although in the case of the Storable example, they won’t make very interesting reading).

The downsides of these databases are quite apparent. As we’ve mentioned already, the lack of concurrent access limits the power of such systems in a multi-user environment. They also suffer from scalability problems due to the sequential nature of the search mechanism. These limitations can be coded around (the concurrent access problem especially so), but there comes a point where you should seriously consider the use of a higher-level storage manager such as DBM files. DBM files also give you access to indexed data and allow nonsequential querying.

Before we discuss DBM files in detail, the following sections give you examples of more sophisticated management tools and techniques, as well as a method of handling concurrent users.