David, it will use RETE but the actual data is retrieved "on-demand"... meaning no previous processing is made, and if it is a list, it will iterate the list every-time, so, it is less efficient than when the data is already in the working memory. It is useful for cases, for instance, when you have a lot of data outside of the working memory, but you are only interested in a small subset of the data... asserting all the data would then be a waste.

   []s
   Edson

2008/8/19 David Boaz <davidb@dbmotion.com>

Hi all,

in the drools manual (6.5.28): "FROM allows the engine to reason over data
not in the working memory".
Will drools use rete to evaluate patterns with a FROM source?

Lets assume the following rule:
WHEN p:Person(age>60), Address(city="NY") FROM p.addresses
will the rule engine match the Address pattern using rete?

and, what about the following rule:
when p:Person(age="m"), Person(age>60) from p
1) will it work?
2) will the age constraint be matched using rete?

Thanks, David
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Edson Tirelli
JBoss Drools Core Development
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