PostgreSQL

Parallel Database Restore, speeding up recovery from backup up to 8 times. Per-Column Permissions, allowing more granular control of sensitive data. Per-database Collation Support, making PostgreSQL more useful in multi-lingual environments. In-place Upgrades through pg_migrator (beta), enabling upgrades from 8.3 to 8.4 without extensive downtime. New Query Monitoring Tools, giving administrators more insight into query activity. Greatly reduced VACUUM overhead through the Visibility Map. New monitoring tools for current queries, query load, and deadlocks.

This release prevents error recursion crashes when encoding conversion
fails, disallows CREATE CONVERSION with the wrong encodings for the
specified conversion function, and fixes xpath() to not modify the path
expression unless necessary, and to make a saner attempt at it when
necessary.

pg_get_ruledef() now parenthesizes negative
constants. ALTER AGGREGATE ... OWNER TO was made
to update pg_shdepend.

A privilege escalation exploit in SECURITY DEFINER
functions was patched.

The server has been changed to reject invalidly-encoded multi-byte characters in all cases. This release rejects unsafe uses of \' in string literals. libpq's string-escaping routines have been modified to be aware of encoding considerations and standard_conforming_strings.