[rules-users] 答复: Performance consideration in rule writing

[Wolfgang Laun]

This ought to be another thread/another subject.

2011/12/26 Zhuo Li <milanello1998 at gmail.com>

>  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 at 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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>
>
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