GDBM

Summary

Ruby extension for GNU dbm (gdbm) – a simple database engine for storing key-value pairs on disk.

Description

GNU dbm is a library for simple databases. A database is a file that stores key-value pairs. Gdbm allows the user to store, retrieve, and delete data by key. It furthermore allows a non-sorted traversal of all key-value pairs. A gdbm database thus provides the same functionality as a hash. As with objects of the Hash class, elements can be accessed with []. Furthermore, GDBM mixes in the Enumerable module, thus providing convenient methods such as find, collect, map, etc.

A process is allowed to open several different databases at the same time. A process can open a database as a “reader” or a “writer”. Whereas a reader has only read-access to the database, a writer has read- and write-access. A database can be accessed either by any number of readers or by exactly one writer at the same time.

Examples

1. Opening/creating a database, and filling it with some entries:

   Example

   Run in Playground

   require 'gdbm'
   
   gdbm = GDBM.new("fruitstore.db")
   gdbm["ananas"]    = "3"
   gdbm["banana"]    = "8"
   gdbm["cranberry"] = "4909"
   gdbm.close
   

2. Reading out a database:

   Example

   Run in Playground

   require 'gdbm'
   
   gdbm = GDBM.new("fruitstore.db")
   gdbm.each_pair do |key, value|
     print "#{key}: #{value}\n"
   end
   gdbm.close
   

   produces

   banana: 8
   ananas: 3
   cranberry: 4909

Links

• www.gnu.org/software/gdbm/