[rules-users] Slow compilation (4h) for a single rule

[Edson Tirelli]

   Listen to what others are saying in this thread... it is very good
advice, specially what wolfgang suggests bellow regarding collapsing evals.

   Also, I just read the example in your link where you have multiple
accumulates in a single rule... that is *bad*....

   For those that attended or saw my presentation on best practices, an
easy way to estimate the performance of accumulates is to remember that the
performance of accumulates in a single rule is polinomial: O(n^a), where
"n" is the number of matching facts and "a" is the number of accumulates
you have in the same rule.

   So, if you have 1 rule with 5 accumulates, the performance will be n^5.
If instead you break the accumulates into 5 rules with one accumulate each,
you get a performance of O(5n) that is much better.

   Edson

On Wed, Jul 25, 2012 at 7:42 AM, Wolfgang Laun <wolfgang.laun at gmail.com>wrote:

> A last effort from my side.
>
> Given any number of bound variables a, b, c: to determine whether an
> arbitrary boolean expression involving arithmetic and comparison
> operators, a single eval() is sufficient and preferable to a CE
> combination involving the CE operators "and", "or", "not" combining
> many evals.
>
> Instead of
>    not( eval( a == 1 ) )
> use
>    eval( ! (a == 1) )  // or better
>    eval( a != 0 )
>
> Instead of
>     eval( a == 1 ) or eval( b == 1 )
> use
>    eval( a == 1 || b == 1 )
>
> Instead of
>     eval( a == 1 ) and eval( b == 1 )
> use
>    eval( a == 1 && b == 1 )
>
> -W
>
> On 25/07/2012, fx242 <drools at fx242.com> wrote:
> > Thanks for your explanation Edson, it makes sense now I think!
> > Basically what you are saying is that there is a limit, beyond which is
> no
> > longer feasible to use more ORs on a rule.
> >
> >
> > Edson Tirelli-4 wrote
> >>
> >> You are trying to avoid the issue. As reported by others, your
> >> conditions should be inside the patterns, not in "or'd" evals in the
> end,
> >> and yes, it is possible to generate rules like that in an automated
> >> program.
> >>
> >
> > Sadly I don't see how, as some of my rules have arbitrary arithmetic
> > involving more than one variable inside the Number(), for more context
> see
> > the example I've put on
> >
> http://drools.46999.n3.nabble.com/drools-arithmetics-without-eval-td3823232.html
> .
> >
> > For this case I think I will try to invert the logic and get rid of the
> > ORs:
> > not(A or B) => not(A) and not(B).
> >
> > Best regards,
> > TL
> >
> >
> >
> >
> > --
> > View this message in context:
> >
> http://drools.46999.n3.nabble.com/Slow-compilation-4h-for-a-single-rule-tp4018855p4018894.html
> > Sent from the Drools: User forum mailing list archive at Nabble.com.
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
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-- 
  Edson Tirelli
  JBoss Drools Core Development
  JBoss by Red Hat @ www.jboss.com
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