Beware with the use of the FROM Conditional Element, because if you are using another fact that doesn't come from the DB and you change them, the FROM CE will be continuously evaluated causing the execution of tons of queries multiple times.
My two cents.
Greetings

2011/2/14 Michael Anstis <michael.anstis@gmail.com>
You can access Objects from external resources using the "from" keyword (in fact the use of this with Hibernate named queries is a documented use-case, IIRC).

The Objects are not however inserted into WorkingMemory using "from" are should therefore be time-constant as their properties will not be included in truth maintenance.

If you require the Objects as Facts in WorkingMemory for the inference engine to reason with, you can write rules using "from" that insert into WorkingMemory.


On 14 February 2011 11:27, hyjshanghai <hyjshanghai@gmail.com> wrote:

As far as I know, Drools can only reason over facts in the working memory. It
can not directly "select" from RDBMS. You have to load in all data items
from the database and validate them in memory by Drools.
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