[rules-users] 'from accumulate' doesn't work on multiple colu mns?..

[Olenin, Vladimir (MOH)]

> Edson wrote:
-------------
3. Regarding the distinct, I'm not sure if it would be good to have such 
"feature". Need further discussion I guess. But on of the ways to work 
around that is just to have a "driver" fact. I mean, if "f1" means a 
financial account, for instance, have a Financial Account fact:
-- End of quote

Yes, that's how I'm dealing with it right now... But you (or Mark?)
mentioned some time ago regarding similar issue ("Convert logic to DRL
rules") that it's better to aviod this kind of 'indexing' and keep the data
model 'flattened' since it'd allow for more optimizations on DROOLS side. In
my case 'Record' fact has 6-7 fields and the type of rules I have would
require to have such index on almost all these fields (which means I'd have
to assert 'unique value' facts for each of the fields). So, I thought this
kind of problem (as well as combination of unique fields) can be solved
easily with having such keyword ('distinct' or 'unique' or smth like that).
I think that even implementation should not be very difficult, since it
would just require to get all facts of particular type and assert a new set
of 'unique value' facts for each of the fields used in the constraint...
Kind of preprocessing step. But I think such index (index of all fields
within particular fact type) might already being created as part of other
algorithms?...

Vlad




-----Original Message-----
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Edson Tirelli
Sent: 07 March 2007 17:43
To: Rules Users List
Subject: Re: [rules-users] 'from accumulate' doesn't work on multiple
columns?..

  Vlad,

Trying to answer both of your e-mails in this one.

1. Right now, accumulate supports only a single Pattern (column), as you 
already realized. That is a limitation we want to remove before the next 
final release, but it is not done yet. I already know how to fix that, 
but didn't had the time to do it yet. We are working hard in the BRMS 
side now. If anyone is willing to help with that, I can provide the 
instructions on how to do the implementation for that feature.

2. Regarding matching the same fact multiple times in a single tuple, 
this is a configuration. In 3.0.x, the default is to not allow the same 
fact to be matched multiple times in a single tuple. In 3.1, the default 
was changed to allow multiple matches. That is why your tested matched 
multiple times. This is one of the BIG warnings we need to add to the 
upgrade documentation.

3. Regarding the distinct, I'm not sure if it would be good to have such 
"feature". Need further discussion I guess. But on of the ways to work 
around that is just to have a "driver" fact. I mean, if "f1" means a 
financial account, for instance, have a Financial Account fact:

rule ...
when
FinancialAccount( $id : id )
Double( doubleValue > 0 ) from accumulate(
Record( finId == $id, $f2 : f2, $val : value )
init( double sum = 0; )
action( sum += ( $f2 < 10 ) ? $val : -$val; )
result( new Double( sum ) ) )
then
// do something
end

Hope it helps.

[]s
Edson

Olenin, Vladimir (MOH) wrote:

> This is as a follow up for the previous question.... It looks like I 
> made a wrong assumption that 'accumulate' can work on multiple columns:
>
> Integer ( intValue > 0) from accumulate (
>
> Record ( f1 == $f1, f2 < 10, $value1 : value )
>
> Record ( f1 == $f1, f2 >= 10, $value2 : value )
>
> Init ( int sum = 0; ),
>
> Action ( sum += $value1 - $value2 ),
>
> Result ( new Integer (sum) )
>
> )
>
> I'm getting an error ('then' is expected or smth like that at the 
> point where the second 'Record' is defined) and the only way to remove 
> the error is to declare one and only one Column constraint... So, it is 
> not possible then to use multiple columns in 'accumulate'? If not, 
> then it would be even more interesting to get some idea on how to 
> approach the kind of problem I mentioned in the previous post.....
>
> Thanks,
>
> Vlad
>
>------------------------------------------------------------------------
>
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>  
>


-- 
 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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