TODO - last modified 2009-07-06

Predicate limit

	Currently you can only have a number of predicates roughly equal to the
max number of open files per process. You can increase this in
/etc/security/limits.conf, but a real fix owuld be better

UNION

	The SPARQL UNION keyword is not that well supported. Simple cases work
OK, but anything complex, eg. combining UNION with OPTIONAL in complex ways
typically gives the wrong result. The is a side effect of the way the query
engine works, and will be difficult to fix. A better solution would be a 2nd,
slower but simple querye engine that follows the SPARQL spec. closely.

Single client

	Currently the 4store backend server only allow one client to connect at
any one time. This is down to the simple locking model. It would be possible to
fix this either by a more sophisiticated locking system, or by allowing
multiple connections but interleaving operations. Either would be a significant
ammount of effort.

Rasqal

	4store only works with version 0.9.15 os rasqal. This wouldn't be too hard
to fix, but probably wont be easy.

Delete single triples

	4store currently only supports delete operations on whole graphs, fixing
that wouldn't be a huge task, but it may impact performance somewhat.

FROM

	There is a basic implementatation in frontend/query.c, but it's
commented out, as it's not safe to have on by default.
