Any question is also about performance consideration. See below example:

Rule “1”

         Dialect “mvel”

         Salience 300

         No-loop true

         When

                   $acctsrc: data(sourceid==1)

                   $reposrc: data((sourceid==2||sourceid==5)&&amount==acctsrc.amount)

         Then

                   …

         End

Two questions here:

1.       In this kind of join conditions, is there any best practice to follow in the rule? I heard from somebody that I need to put data who have less # of transactions first in my when expression. For example, if I have less number of $reposrc transactions in facts, I should put it ahead of $acctsrc to gain better performance. Is this valid?

Correct: narrowing down the number of joins is best practice.

2. Do we know how to create an event listener in the rule for logging purpose rather than standard log4j? It was recommended in some other articles as well. Is this also valid? (http://www.technologyblue.com/docs/presentations/DroolsBestPractices.pdf);

An event listener as provided by Drools for rule and WM events is not to be confused with a logging service, so your question doesn't make much sense. The big difference is that a listener gets informed about all it is set up to listen to, whereas calls to Looger.info() need to be written wherever logging should be done. This could be in listener code reacting to an event, or anyplace else, as in the RHS of some rules in the quoted presentation.

Ultimately, is there any place I can find a best practice of rule development as a generic guide?

Not a single place that I know of. Perhaps if you post this as a separate thread with a fitting topic.

-W

Best

Abe

发件人: Zhuo Li [mailto:milanello1998@gmail.com]
发送时间: 2011年12月26日 16:51
收件人: 'Rules Users List'
主题: Performance consideration in rule writing

Hi, team,

I have some quick questions here regarding performance best practices of rule writing. See below two pieces of rules:

Rule “1”

         Salience 100

         No-loop true

         When $txn : data(sourceid == 5&&txnjustify==”995”&&eval(creditOption($txn)==1)&&eval(isGCSwitch($txn))&&isCurrencyEquals($txn)==0&&compareToPostThreshold($txn)==2);

         Then

                   …

         End

Rule “2”

         Salience 100

         No-loop true

         When $txn : data(sourceid == 5&&txnjustify==”995”&&eval(creditOption($txn)==1)&&eval(isGCSwitch($txn))&&isCurrencyEquals($txn)==0&&compareToPostThreshold($txn)==1);

         Then

                  …

         End

Questions:

1.       Will I gain better performance if I put the rule differentiator condition “compareToPostThreshold($txn)==2” at the beginning of both rule 1 and 2?

2.       I saw salaboy’s video claiming that to avoid using eval() in the rule. Do we have any alternative way to do that from a performance consideration or I’d better collect/ prepare all the data before I send them into the session?

3.       What’s you guys’ naming convention for rule’s salience?

PS: my Drools version is 5.2.0.

Best regards

Abe

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