The management of data in telecommunications system has many aspects, thereof some, but not all, are addressed by traditional commercial Database Management Systems (DBMSs). In particular the high level of fault tolerance that is required in many nonstop systems, combined with requirements on the DBMS to run in the same address space as the application, have led us to implement a new DBMS, called Mnesia.
Mnesia is implemented in, and tightly connected to Erlang. It provides the functionality that is necessary for the implementation of fault tolerant telecommunications systems.
Mnesia is a multiuser distributed DBMS specially made for industrial telecommunications applications written in Erlang, which is also the intended target language. Mnesia tries to address all the data management issues required for typical telecommunications systems. It has a number of features that are not normally found in traditional databases.
In telecommunications applications, there are different needs from the features provided by traditional DBMSs. The applications now implemented in Erlang need a mixture of a broad range of features, which generally are not satisfied by traditional DBMSs. Mnesia is designed with requirements like the following in mind:
Mnesia is designed with the typical data management problems of telecommunications applications in mind. This sets Mnesia apart from most other DBMS. Hence Mnesia combines many concepts found in traditional databases such as transactions and queries with concepts found in data management systems for telecommunications applications, for example:
Mnesia is also interesting because of its tight coupling to Erlang, thus almost turning Erlang into a database programming language. This has many benefits, the foremost is that the impedance mismatch between the data format used by the DBMS and the data format used by the programming language, which is used to manipulate the data, completely disappears.
Mnesia contains the following features that combine to produce a fault-tolerant, distributed DBMS written in Erlang:
Details of these features are described in the following sections.
Query List Comprehension (QLC) can be used with Mnesia to produce specialized functions that enhance the operational ability of Mnesia. QLC has its own documentation as part of the OTP documentation set. The main features of QLC when used with Mnesia are as follows:
For information about QLC, see the
qlc manual page in STDLIB.
Use Mnesia with the following types of applications:
Mnesia is not as appropriate with the following types of applications:
dets, which is a disc-based version of the module
ets. For information about
dets, see the
detsmanual page in STDLIB.
disk_logby preference. For information about
disk_log, see the
disk_logmanual page in Kernel.
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Licensed under the Apache License, Version 2.0.