Skip to Main Content
Practical PostgreSQL
book

Practical PostgreSQL

by Joshua D. Drake, John C. Worsley
January 2002
Intermediate to advanced content levelIntermediate to advanced
640 pages
16h 39m
English
O'Reilly Media, Inc.
Content preview from Practical PostgreSQL

Begin

Starts a chained-mode transaction block.

Synopsis

BEGIN [ WORK | TRANSACTION ]

Parameters

WORK | TRANSACTION

A pair of optional noise keywords. They can be ignored, or used to make your SQL more readable.

Results

BEGIN

The message returned when a transaction begins.

NOTICE: BEGIN: already a transaction in progress

The notice returned if a transaction is already in progress within your PostgreSQL session. You cannot nest multiple transactions. The transaction you have in progress is not altered when this happens.

Description

PostgreSQL executes transactions in unchained mode by default. Also called autocommit, this mode encapsulates each user statement in an implicit transaction, and automatically finalizes the transaction by either committing the modification, or performing a rollback, depending on whether or not the execution was successful.

Using BEGIN specifies that you want to enter a transaction block using chained mode, in which statements will be queued by the database, and then sent in a single transaction when the database receives a COMMIT command. Alternatively, the queued statements can be discarded by a ROLLBACK, or by an unexpected disconnection.

Chained mode can be useful when you are working with multiple related tables, and also to increase database performance in general. Executing statements in chained mode uses less CPU and disk resources, as there is only one commit needed per block of statements executed.

When a transaction is committed, the database will attempt to ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

PostgreSQL: Up and Running, 2nd Edition

PostgreSQL: Up and Running, 2nd Edition

Regina O. Obe, Leo S. Hsu
Learning PostgreSQL 11 - Third Edition

Learning PostgreSQL 11 - Third Edition

Christopher Travers, Andrey Volkov
Learn PostgreSQL

Learn PostgreSQL

Luca Ferrari, Enrico Pirozzi
PostgreSQL 13 Cookbook

PostgreSQL 13 Cookbook

Vallarapu Naga Avinash Kumar

Publisher Resources

ISBN: 9781449309770Supplemental ContentErrata Page