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diff --git a/lib/mnesia/doc/src/Mnesia_chap1.xml b/lib/mnesia/doc/src/Mnesia_chap1.xml index 9af81c85cb..9dfeb5efe4 100644 --- a/lib/mnesia/doc/src/Mnesia_chap1.xml +++ b/lib/mnesia/doc/src/Mnesia_chap1.xml @@ -1,23 +1,24 @@ -<?xml version="1.0" encoding="latin1" ?> +<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE chapter SYSTEM "chapter.dtd"> <chapter> <header> <copyright> - <year>1997</year><year>2009</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> - The contents of this file are subject to the Erlang Public License, - Version 1.1, (the "License"); you may not use this file except in - compliance with the License. You should have received a copy of the - Erlang Public License along with this software. If not, it can be - retrieved online at http://www.erlang.org/. - - Software distributed under the License is distributed on an "AS IS" - basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See - the License for the specific language governing rights and limitations - under the License. + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. </legalnotice> @@ -31,235 +32,82 @@ <rev>C</rev> <file>Mnesia_chap1.xml</file> </header> - <p>This book describes the Mnesia DataBase Management - System (DBMS). <em>Mnesia</em> is a distributed Database Management - System, appropriate for telecommunications applications and other - Erlang applications which require continuous operation and soft - real-time properties. It is one section of the Open Telecom Platform - (OTP), which is a control system platform for building - telecommunications applications.</p> - - <section> - <title>About Mnesia</title> - <p>The management of data in telecommunications system has many - aspects whereof some, but not all, are addressed by traditional - commercial DBMSs (Data Base Management Systems). In particular the - very high level of fault tolerance which 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 brand new - DBMS. called Mnesia. Mnesia is implemented in, and very tightly - connected to, the programming language Erlang and 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 the symbolic programming language Erlang, which is also - the intended target language. Mnesia tries to address all of the data - management issues required for typical telecommunications systems and - it has a number of features that are not normally found in traditional - databases. <br></br> - - In telecommunications applications there are different needs - from the features provided by traditional DBMSs. The applications now - implemented in the Erlang language 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:</p> - <list type="ordered"> - <item>Fast real-time key/value lookup</item> - <item>Complicated non real-time queries mainly for - operation and maintenance</item> - <item>Distributed data due to distributed - applications</item> - <item>High fault tolerance</item> - <item>Dynamic re-configuration</item> - <item>Complex objects</item> - </list> - <p>What - sets Mnesia apart from most other DBMSs is that it is designed with - the typical data management problems of telecommunications applications - in mind. Hence Mnesia combines many concepts found in traditional - databases, such as transactions and queries with concepts found in data - management systems for telecommunications applications, such as very - fast real-time operations, configurable degree of fault tolerance (by - means of replication) and the ability to reconfigure the system without - stopping or suspending it. Mnesia is also interesting due to its tight - coupling to the programming language Erlang, thus almost turning Erlang - into a database programming language. This has many benefits, the - foremost is that - the impedance mismatch between data format used by the - DBMS and data format used by the programming language, which is used - to manipulate the data, completely disappears. <br></br> -</p> - </section> - - <section> - <title>The Mnesia DataBase Management System (DBMS)</title> - <p></p> + <p>The <c>Mnesia</c> application provides a heavy duty real-time + distributed database.</p> <section> - <title>Features</title> - <p>Mnesia contains the following features which combine to produce a fault-tolerant, - distributed database management system written in Erlang: - </p> + <title>Scope</title> + <p>This User's Guide describes how to + build <c>Mnesia</c> database applications, and how to integrate + and use the <c>Mnesia</c> database management system with + OTP. Programming constructs are described, and numerous + programming examples are included to illustrate the use of + <c>Mnesia</c>.</p> + <p>This User's Guide is organized as follows:</p> <list type="bulleted"> - <item>Database schema can be dynamically reconfigured at runtime. + <item><seealso marker="Mnesia_overview">Mnesia</seealso> + provides an introduction to + <c>Mnesia</c>. + </item> + <item><seealso marker="Mnesia_chap2">Getting Started</seealso> + introduces <c>Mnesia</c> with an example database. Examples + are included how to start an Erlang session, specify a + <c>Mnesia</c> database directory, initialize a database + schema, start <c>Mnesia</c>, and create tables. Initial + prototyping of record definitions is also discussed. + </item> + <item><seealso marker="Mnesia_chap3">Build a Mnesia + Database</seealso> more formally describes the steps + introduced in the previous section, namely the <c>Mnesia</c> + functions that define a database schema, start <c>Mnesia</c>, + and create the required tables. + </item> + <item><seealso marker="Mnesia_chap4">Transactions and Other Access Contexts</seealso> + describes the transactions properties that make <c>Mnesia</c> into + a fault tolerant, real-time distributed database management + system. This section also describes the concept of locking + to ensure consistency in tables, and "dirty + operations", or short cuts, which bypass the transaction system + to improve speed and reduce overheads. </item> - <item>Tables can be declared to have properties such as location, - replication, and persistence. + <item><seealso marker="Mnesia_chap5">Miscellaneous Mnesia + Features</seealso> describes features that enable the + construction of more complex database applications. These + features include indexing, checkpoints, distribution and fault + tolerance, disc-less nodes, replication manipulation, local + content tables, concurrency, and object-based programming in + <c>Mnesia</c>. </item> - <item>Tables can be moved or replicated to several nodes to improve - fault tolerance. The rest of the system can still access the tables - to read, write, and delete records. + <item><seealso marker="Mnesia_chap7">Mnesia System + Information</seealso> describes the files contained in the + <c>Mnesia</c> database directory, database configuration data, + core and table dumps, as well as the important subject of + backup, fall-back, and disaster recovery principles. </item> - <item>Table locations are transparent to the programmer. - Programs address table names and the system itself keeps track of - table locations. + <item><seealso marker="Mnesia_chap8">Combine Mnesia with + SNMP</seealso> is a short section that outlines <c>Mnesia</c> + integrated with SNMP. </item> - <item>Database transactions can be distributed, and a large number of - functions can be called within one transaction. + <item><seealso marker="Mnesia_App_A">Appendix A: Backup + Callback Interface</seealso> is a program listing of the + default implementation of this facility. </item> - <item>Several transactions can run concurrently, and their execution is - fully synchronized by the database management system. - Mnesia ensures that no two processes manipulate data simultaneously. + <item><seealso marker="Mnesia_App_B">Appendix B: Activity + Access Callback Interface</seealso> is a program outlining + one possible implementation of this facility. </item> - <item>Transactions can be assigned the property of being executed on - all nodes in the system, or on none. Transactions can also be bypassed - in favor of running so called "dirty operations", which reduce - overheads and run very fast. + <item><seealso marker="Mnesia_App_C">Appendix C: Fragmented + Table Hashing Callback Interface</seealso> is a program + outlining one possible implementation of this facility. </item> </list> - <p>Details of these features are described in the following sections.</p> - </section> - <p></p> - - <section> - <title>Add-on Applications</title> - <p>QLC and Mnesia Session can be used in conjunction with Mnesia to produce - specialized functions which enhance the operational ability of Mnesia. - Both Mnesia Session and QLC have their own documentation as part - of the OTP documentation set. Below are the main features of Mnesia Session - and QLC when used in conjunction with Mnesia:</p> - <list type="bulleted"> - <item><em>QLC</em> has the ability to optimize the query - compiler for the Mnesia Database Management System, essentially making - the DBMS more efficient.</item> - <item><em>QLC</em>, can be used as a database programming - language for Mnesia. It includes a notation called "list - comprehensions" and can be used to make complex database - queries over a set of tables.</item> - <item><em>Mnesia Session</em> is an interface for the Mnesia Database - Management System</item> - <item><em>Mnesia Session</em> enables access to the - Mnesia DBMS from foreign programming languages (i.e. other - languages than Erlang).</item> - </list> - <p></p> - - <section> - <title>When to Use Mnesia</title> - <p>Use Mnesia with the following types of applications: - </p> - <list type="bulleted"> - <item>Applications that need to replicate data. - </item> - <item>Applications that perform complicated searches on data. - </item> - <item>Applications that need to use atomic transactions to - update several records simultaneously. - </item> - <item>Applications that use soft real-time characteristics. - </item> - </list> - <p>On the other hand, Mnesia may not be appropriate with the - following types of applications: - </p> - <list type="bulleted"> - <item>Programs that process plain text or binary data files - </item> - <item>Applications that merely need a look-up dictionary - which can be stored to disc can utilize the standard - library module <c>dets</c>, which is a disc based version - of the module <c>ets</c>. - </item> - <item>Applications which need disc logging facilities can - utilize the module <c>disc_log</c> by preference. - </item> - <item>Not suitable for hard real time systems. - </item> - </list> - </section> - </section> - - <section> - <title>Scope and Purpose</title> - <p>This manual is included in the OTP document set. It describes - how to build Mnesia database applications, and how to integrate - and utilize the Mnesia database management system with - OTP. Programming constructs are described, and numerous - programming examples are included to illustrate the use of - Mnesia. - </p> </section> <section> <title>Prerequisites</title> - <p>Readers of this manual are assumed to be familiar with system - development principles and database management systems. Readers - are also assumed to be familiar with the Erlang programming - language.</p> - </section> - - <section> - <title>About This Book</title> - <p>This book contains the following chapters: - </p> - <list type="bulleted"> - <item>Chapter 2, "Getting Started with Mnesia", introduces - Mnesia with an example database. Examples are shown of how to - start an Erlang session, specify a Mnesia database directory, - initialize a database schema, start Mnesia, and create - tables. Initial prototyping of record definitions is also - discussed. - </item> - <item>Chapter 3, "Building a Mnesia Database", more formally - describes the steps introduced in Chapter 2, namely the Mnesia - functions which define a database schema, start Mnesia, and - create the required tables. - </item> - <item>Chapter 4, "Transactions and other access contexts", - describes the transactions properties which make Mnesia into a - fault tolerant, real-time distributed database management - system. This chapter also describes the concept of locking in - order to ensure consistency in tables, and so called "dirty - operations", or short cuts which bypass the transaction system - to improve speed and reduce overheads. - </item> - <item>Chapter 5, "Miscellaneous Mnesia Features", describes - features which enable the construction of more complex - database applications. These features includes indexing, - checkpoints, distribution and fault tolerance, disc-less - nodes, replication manipulation, local content tables, concurrency, - and object based programming in Mnesia. - </item> - <item>Chapter 6, "Mnesia System Information", describes the - files contained in the Mnesia database directory, database - configuration data, core and table dumps, as well as the - important subject of backup, fall-back, and disaster recovery - principles. - </item> - <item>Chapter 7, "Combining Mnesia with SNMP", is a short - chapter which outlines Mnesia integrated with SNMP. - </item> - <item>Appendix A, "Mnesia Errors Messages", lists Mnesia error - messages and their meanings. - </item> - <item>Appendix B, "The Backup Call Back Interface", is a - program listing of the default implementation of this facility. - </item> - <item>Appendix C, "The Activity Access Call Back Interface", - is a program outlining of one possible implementations of this facility. - </item> - </list> + <p>It is assumed that the reader is familiar with the Erlang + programming language, system development principles, and + database management systems.</p> </section> - </section> </chapter> |