Highlights of this release are as follows:
Vacuuming no longer locks tables, thus allowing normal user access during the vacuum. A new "VACUUM FULL" command does old-style vacuum by locking the table and shrinking the on-disk copy of the table.
There is no longer a problem with installations that exceed four billion transactions.
OID's are now optional. Users can now create tables without OID's for cases where OID usage is excessive.
The system now computes histogram column statistics during "ANALYZE", allowing much better optimizer choices.
A new MD5 encryption option allows more secure storage and transfer of passwords. A new Unix-domain socket authentication option is available on Linux and BSD systems.
Administrators can use the new table access statistics module to get fine-grained information about table and index usage.
Program and library messages can now be displayed in several languages.
.. with many many more bug fixes, enhancements and performance related changes ...