[rules-users] Will the alternative lead to a better performance?

[Premkumar Stephen]

Hi Edson,

Thanks for your reply.

WRT your reply below (highlighted):
In our environment, we only have one class and several instances of that
class.

We currently do not use the "==" constraint and we do a equals() on the name
string. However, I am going to use "==" since there will be only one object
with a particular name.

Also, can you define what the number for "huge" is? How many buckets get
defined initially for the hashing. Can I modify the initial size of this
collection so that I will not have clashes. ( I happen to know exactly how
many objects will be thrown into the engine)

Is this set through configuration or would I have to recompile code to do
this?

Thanks,
Prem

On 3/23/07, Edson Tirelli <tirelli at post.com> wrote:
>
>
>    Stephen,
>
>    As long as you use an "==" constraint as your example shows, the
> first alternative will be more performatic. This is because drools
> indexes facts based on your constraints. So, your first case will
> require a single "==" comparison to find user name "A" and a single
> comparison to find user name "B". Of course, if you have huge amound of
> objects where hashcode for name start to clash, you may have more than
> one comparison, but the effect is negligible when compared to all other
> costs of having that many facts.
>
>    Second alternative works and will also hash object types, but it will
> create a lot more infrastructure classes and Rete Nodes to deal with
> your 500 different classes. So it is a worst alternative for the
> proposed scenario.
>
>    []s
>    Edson
>
>
> Premkumar Stephen wrote:
>
> > Hi,
> >
> > Consider that I have 500 instances of interface userI. Now, there are
> > 3000 rules currently written based on a combination of these instances.
> >
> > if {
> >      $a : userI (name = "A")
> >      $b : userI (name = "B")
> > }
> > then
> > {
> >  //do some actions
> > }
> >
> > How many tests are needed for a match in the RETE network for this rule?
> >
> > If I created 500 classes, one for each object, such as UserA
> > implements userI and so on... my rule will look like:
> >
> > if {
> >      $a : UserA()
> >      $b : UserB()
> > }
> > then
> > {
> >  //do some actions
> > }
> >
> > Will this lead to better performance since there will only be one such
> > instance of this object?
> >
> > As for class-loading concerns, will there be a parsing/memory penalty
> > to be paid for having 500 classes now instead of one?
> >
> > Thanks!
> >
> >------------------------------------------------------------------------
> >
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> >https://lists.jboss.org/mailman/listinfo/rules-users
> >
> >
>
>
> --
> Edson Tirelli
> Software Engineer - JBoss Rules Core Developer
> Office: +55 11 3124-6000
> Mobile: +55 11 9218-4151
> JBoss, a division of Red Hat @ www.jboss.com
>
>
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>



-- 
Regards,
Prem
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