The primary goal for Firebird 2.5 free software database engine was to establish the basics for a new threading architecture that is almost entirely common to the Superserver, Classic and Embedded models, taking in lower level synchronization and thread safety generally. Although SQL enhancements are not a primary objective of this release, for the first time, user management becomes accessible through SQL CREATE/ALTER/DROP USER statements and syntaxes for ALTER VIEW and CREATE OR ALTER VIEW are implemented. PSQL improvements include the introduction of autonomous transactions and ability to query another database via EXECUTE STATEMENT.