Re: [rules-users] Advantages and Disadvantages of "from"

Hi, On Fri, May 30, 2008 at 5:06 PM, Thalupula Ravi <thalupularavi(a)gmail.com&gt; wrote: > > Hi, > > Can some one describe about advantages and disadvantages of below to > approaches > > 1. Interacting Database for information in rule ( using "from" or > something > else)? > > or > > 2. Required information supplied to rules in the form facts at one shot > by > client instead of again hitting the database. > > Thanks for your help:handshake: if you're going to use "from" in your rules, you should make sure that you provide some extra methods in your DAOs instead of only some generic "getAll()" method. This way, if there are some hundred thousands records in your database, Drools will not have to instantiate an object for each of them since the DAO/database can filter out those objects that are not relevant to the use case. If, for example, you write some rule that handles order processing, you could write a DAO method "getUnprocessedOrders()" which will ignore all orders that are already processed. AFAIK Drools does no sharing/caching of objects retrieved via equivalent "from" calls in different rules. When planning my current project, I quickly found that manually retrieving the objects and inserting them into the working memory gave me somewhat more flexibility but that of course depends on the use case at hand. Best regards Marcus _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users