Preface
This book is the official documentation of PostgreSQL. It is being
written by the PostgreSQL developers and other volunteers in
parallel to the development of the PostgreSQL software. It
describes all the functionality that the current version of
PostgreSQL officially supports.
To make the large amount of information about PostgreSQL manageable,
this book has been organized in several parts. Each part is
targeted at a different class of users, or at users in different
stages of their PostgreSQL experience:
is an informal introduction for new users.
documents the SQL query
language environment, including data types and functions, as well
as user-level performance tuning. Every
PostgreSQL> user should read this.
describes the installation and
administration of the server. Everyone that runs a PostgreSQL
server, be it for private use or for others, should read this
part.
describes the programming
interfaces for PostgreSQL client programs.
contains information for
advanced users about the extensibility capabilities of the
server. Topics are, for instance, user-defined data types and
functions.
contains information about the syntax
of SQL commands, client and server programs. This part supports
the other parts with structured information sorted by command or
program.
What is PostgreSQL?
PostgreSQL is an object-relational
database management system (ORDBMS) based on
POSTGRES, Version 4.2, developed
at the University of California at Berkeley Computer Science
Department. POSTGRES pioneered many concepts that only became
available in some commercial database systems much later.
PostgreSQL is an open-source descendant
of this original Berkeley code. It supports SQL92 and SQL99 and
offers many modern features:
complex queries
foreign keys
triggers
views
transactional integrity
multiversion concurrency control
Also, PostgreSQL can be extended by the user in many ways, for
example by adding new
data types
functions
operators
aggregate functions
index methods
procedural languages
And because of the liberal license, PostgreSQL can be used,
modified, and distributed by everyone free of charge for any
purpose, be it private, commercial, or academic.
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