Using SQLite

Name

read_uncommitted — Enable reads of uncommitted data from database cache

Common Usage

PRAGMA read_uncommitted;
PRAGMA read_uncommitted = switch;

Description

The read_uncommitted pragma gets or sets the shared cache isolation method.

If the same process opens the same database multiple times, SQLite can be configured to allow those connections to share a single cache instance. This is helpful in very low-memory situations, such as low-cost embedded systems.

This pragma controls which locks are required to access the shared cache. Setting this pragma relaxes some of the locking requirements and allows connections to read from the cache, even if another connection is in the middle of a transaction. This allows better concurrency, but it also means that readers may see data the writer has not committed, breaking transaction isolation.

The read_uncommitted pragma is only applicable to systems that use shared cache mode, which is normally not used on desktop systems. If you are using shared cache mode and may have a need for this pragma, please see the source code and online documentation at http://www.sqlite.org/sharedcache.html for more information.