**** SECONDO Release Notes ****


2009-08-11 Notes on Release 2.9
===============================================================================

A plugin system has been established. A Secondo plugin is an optional extension
to parts of the database system (new algebra, new viewers, new display classes, 
and/ or extensions of the optimizer) provided as a single zip-file. Besides the 
parts containing the source code (i.e. source files and code sections), a plugin 
contains an XML file containing information about where the new code is to place, 
the name of the extension etc. 
This allows for an automatical installation of an extension using a tool which 
is part of a Secondo distribution. So, if the inventor of a new data structure 
or of a new algorithm provides it as a secondo plugin, other researcher can 
compare their solutions with this approach without the effort of reimplementing 
the algorithms/ data structures.

The following Algebra are now distributed as plugins:

    * X-Tree and M-Tree
    * Periodic

The following algebras are all NEW and are distributed as plugins:

    * Nearest Neighbor
    * TB-Tree
    * Spatiotemporal Pattern Queries

This release includes various bug fixes, improving the general stability.

An optional type inference module and optional new cost functions have been 
added to the optimizer. Also, more information on indexes and files is available
in order to implement smarter cost functions. The optimizer now can handle 
subqueries and can optimize the mayority of the BerlinMOD/R benchmark queries.