removed, but this should still function correctly on a.out systems. This
package was originally submitted by D'Arcy J.M. Cain, but with major
overhauling by me.
Closes PR#7865 and relevant part of PR#8299.
Major changes from version 6.4.2:
Multi-version concurrency control(MVCC)
This removes our old table-level locking, and replaces it with a
locking system that is superior to most commercial database
systems. In a traditional system, each row that is modified is
locked until committed, preventing reads by other users. MVCC
uses the natural multi-version nature of PostgreSQL to allow
readers to continue reading consistent data during writer
activity. Writers continue to use the compact pg_log transaction
system. This is all performed without having to allocate a lock
for every row like traditional database systems. So, basically,
we no longer are restricted by simple table-level locking; we
have something better than row-level locking.
Hot backups from pg_dump
pg_dump takes advantage of the new MVCC features to give a
consistant database dump/backup while the database stays online
and available for queries.
Numeric data type
We now have a true numeric data type, with user-specified
precision.
Temporary tables
Temporary tables are guaranteed to have unique names within a
database session, and are destroyed on session exit.
New SQL features
We now have CASE, INTERSECT, and EXCEPT statement support. We
have new LIMIT/OFFSET, SET TRANSACTION ISOLATION LEVEL, SELECT
... FOR UPDATE, and an improved LOCK TABLE command.
Speedups
We continue to speed up PostgreSQL, thanks to the variety of
talents within our team. We have sped up memory allocation,
optimization, table joins, and row transfer routines.
Ports
We continue to expand our port list, this time including
WinNT/ix86 and NetBSD/arm32.
Interfaces
Most interfaces have new versions, and existing functionality
has been improved.
Documentation
New and updated material is present throughout the
documentation. New FAQs have been contributed for SGI and AIX
platforms. The Tutorial has introductory information on SQL from
Stefan Simkovics. For the User's Guide, there are reference pages
covering the postmaster and more utility programs, and a new
appendix contains details on date/time behavior. The
Administrator's Guide has a new chapter on troubleshooting from
Tom Lane. And the Programmer's Guide has a description of query
processing, also from Stefan, and details on obtaining the
Postgres source tree via anonymous CVS and CVSup.
