This manual is part of the official reference documentation for PostgreSQL 9.0. It describes the SQL language specification as implemented by PostgreSQL, including syntax, data types, functions and operators, indexes and transactions. The new XML datatypes and full-text index support of PostgreSQL 9 are also fully documented.This volume is part of a set. The separate Volume 1B "SQL Command Reference" (ISBN 978-1-906966-05-8) contains the documentation for every PostgreSQL command from ABORT to VALUES. PostgreSQL client and server command-line tools are also documented in Volume 1B. Volumes 1A and 1B are intended to be used together. The further additional volumes of this series are Volume 2, the "Programming Guide" (ISBN 978-1-906966-06-5), and Volume 3, the "Server Administration Guide" (ISBN 978-1-906966-07-2).For each copy of this manual sold 1 USD is donated to the PostgreSQL project by the publisher, Network Theory Ltd.