Wolfgang,
Unfortunately, it would be very difficult to introduce a procedural/algorithmic "branch" into the program flow.
�
Would it be possible to mimic a procedural approach within the rule using an accumulate function to extract the desired array element and then process the rest of the rule's login?
The example withholds all the details. I don't see any array elements.
The rule determines a triplet of Data facts that's "close together", and this is done for all Data objects.
It would be better to have a "rover" Data pointer that does this for the "current", and moves on to the
next "after", computing another "after". Start the rover with a minimum position.
But, given you have all the Data facts, this can be computed procedurally, triggered by a rule, done
on the rule's RHS.
-W
�
Looks like an anti-pattern to me: you can expect O(n^3) effort for inserting Data facts.
This is something where a procedural/algorithmic solution is preferable to a
rule based solution.
-W
�
On 4 May 2012 18:44, Mike Goldner
<mike@thegoldners.com> wrote:
I have a rule that is suffering severe performance degradation as I insert
facts into the (stateful) session. �In my simplified example, the first
100 fact insertions take less than 10ms per fact. �By the 1000th fact,
insertions are taking about 850ms per fact. �In production, the impact is
much more severe, reaching 5000ms or more by the 1000th insertion. �The
number of facts per execution can vary from a few hundred to a few
thousand.
I've created a simplified example that demonstrates the problem: �Imagine
that there is a line plotted through a 3-dimensional plane and it is
necessary to ensure that each plotted coordinate is an equal distance from
the adjacent coordinates. �I realize that the math isn't correct, but it
is sufficient for the example.
The constraint (and source of performance degradation) imposed by my data
source is that the plane (X, Y, or Z) is variable and it is defined by an
separate index that serves as a pointer into the coordinate list. �If I
remove the function calls, the problem disappears.
Any suggestions on how I could rewrite the rule?
Here is my rule:
package test;
declare Data
� � � �plane : int
� � � �coordinates : java.util.List
end
rule "Performance degradation with functions."
� � � �dialect "mvel"
� � � �when
� � � � � � � �$current : Data( $currentPosition : getPosByAxis(plane, coordinates) )
� � � � � � � �$before : Data( $beforePosition : getPosByAxis(plane, coordinates) <
$currentPosition)
� � � � � � � �not Data( getPosByAxis(plane, coordinates) > $beforePosition && <
$currentPosition)
� � � � � � � �$after : Data($afterPosition : getPosByAxis(plane, coordinates) >
$currentPosition)
� � � � � � � �not Data(getPosByAxis(plane, coordinates) < $afterPosition && >
$currentPosition)
� � � � � � � �eval ( ($currentPosition - $beforePosition) == ($afterPosition -
$currentPosition) )
� � � �then
� � � � � � � �System.out.println("Rule RHS fired.");
end
function Double getPosByAxis(int plane, java.util.List coordinates) {
� � � �return (Double) coordinates.get(plane);
}
Thanks,
Mike Goldner
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