May be I have not put the question right. We have a drool rule that is running extremely
slow for large sets of data. The rule is something like:
For every object A, perform action if there does not exist an object B such that A.id =
B.id.
And the corresponding drool rule is as follows:
when
A()
not(exists B(A.id = id))
then
action......
The performance is bad because of not exists clause here. We have got OOM exceptions with
relatively large amounts of data for this rule. To improve performance, we basically
hacked the rule/code into something like this:
Create a global variable x that is a HashSet of all ids of object A, and the drool rule
now is:
global java.util.HashSet x;
when
B()
eval
(
! (x.contains(b.id) )
)
then
action.....
This obviously is performing much better with hashes involved. But, I don't like the
fact that we have to write the logic of this rule at two places. I would rather create
this variable x (don't care whether it is global or temporarily bound) in the rule
itself and use it in the condition to help performance and have all logic for the rule at
one place.
Is there a way to generate this hashset x in the condition part of the rule itself? Yes, I
understand that I am trying to mix up the procedural part of code with drool code. But, I
was just wondering if this is possible to keep the java code clean and have the
intelligence of information that the rule needs to be evaluated in the rule itself.
Hope this clears some doubts.
Thanks
Malay Shah
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On
Behalf Of Greg Barton
Sent: Friday, August 21, 2009 4:44 PM
To: Rules Users List
Subject: Re: [rules-users] populating global variable in Condition Section?
This is a galactically bad idea. Using a global in this way is inherently unsafe as
there's no guarantee that ebtween the time you set the var and when it's used
later in the condition that the value is the same. What is your reason for wanting to use
a global in this way? You should use a temporary bound variable instead.
--- On Fri, 8/21/09, Shah, Malay <Malay.Shah(a)morganstanley.com> wrote:
From: Shah, Malay <Malay.Shah(a)morganstanley.com>
Subject: [rules-users] populating global variable in Condition Section?
To: rules-users(a)lists.jboss.org
Date: Friday, August 21, 2009, 3:19 PM
Hi,
Is it possible
to populate a global variable in
the condition section of the
drool rule, and use it later in the condition itself?
I currently have a
global HashSet variable that I construct before firing the rule, but I
would like this code of constructing this global variable to be with
the drool rule itself. Any help on this would be much appreciated.
Thanks
Malay
NOTICE: If received in error, please
destroy, and notify sender. Sender does not intend to waive
confidentiality or privilege. Use of this email is
prohibited when received in error. We may monitor and store emails to the extent
permitted by applicable law.
-----Inline Attachment Follows-----
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
--------------------------------------------------------------------------
NOTICE: If received in error, please destroy, and notify sender. Sender does not intend to
waive confidentiality or privilege. Use of this email is prohibited when received in
error. We may monitor and store emails to the extent permitted by applicable law.