Editing Portal:Databases (section)

=== Flat files, DBM files, and tied hashes ===

Before SQL databases became common in every small application, Perl programmers often used simple file-based storage. This included plain text files, CSV-like formats, serialized Perl structures, and DBM-style key-value databases. Perl’s built-in hash data structure made key-value storage feel natural, and Perl’s `tie` mechanism allowed a hash to be connected to an external storage engine.

Classic modules such as `SDBM_File`, `NDBM_File`, `GDBM_File`, `AnyDBM_File`, and `DB_File` allowed Perl programs to treat persistent database files almost like ordinary Perl hashes. `AnyDBM_File` exists as a framework for choosing among several DBM packages, including Berkeley DB through `DB_File`, GDBM, SDBM, NDBM, and ODBM.<ref>Perldoc, “AnyDBM_File,” https://perldoc.perl.org/AnyDBM_File, accessed July 3, 2026.</ref>