4:19 p.m.
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
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4:44 p.m.
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
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5:11 p.m.
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
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rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
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5:54 p.m.
<quote>
It is rather common for people to write something like "(not (exists (A))),"
but this is just a very inefficient way to write (not (A)).
</quote>
Kudos to Ernest Friedman-Hill to put this sentence into the Jess
documentation.
Maybe I should quote hiom in the Drools Expert doc ;-)
-W
On Fri, Aug 21, 2009 at 11:11 PM, Shah, Malay
<Malay.Shah(a)morganstanley.com>wrote:
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(a)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
>
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3 comments
3 participants
participants (3)
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Greg Barton -
Shah, Malay -
Wolfgang Laun