* Use a separate interpreter for each calling SQL userid in PL/Perl and PL/Tcl
* Improve pg_get_expr() security fix so that the function can still be used on
the output of a sub-select
* Fix incorrect placement of placeholder evaluation
* Fix join removal's handling of placeholder expressions
* Fix possible duplicate scans of UNION ALL member relations
* Prevent infinite loop in ProcessIncomingNotify() after unlistening
* Prevent show_session_authorization() from crashing within autovacuum
processes
* Re-allow input of Julian dates prior to 0001-01-01 AD
* Make psql recognize "DISCARD ALL" as a command that should not be encased in
a transaction block in autocommit-off mode
* Update build infrastructure and documentation to reflect the source code
repository's move from CVS to Git
9.0 includes more major features than any release before it, including:
* Hot standby
* Streaming replication
* In-place upgrades
* 64-bit Windows builds
* Easy mass permissions management
* Anonymous blocks and named parameter calls for stored procedures
* New windowing functions and ordered aggregates
... and many more. For details on the over 200 additions and improvements in
this version, developed by over a hundred contributors, please see the release
notes.