yes
So I take it that all of these permit indexing:
<fieldname> == <literal>
<fieldname> == <variable>yes
<fieldname> == <qualified-identifier>yes
<fieldname> == <expression> # not necessarily parenthesized any more!no, not yet, but will do eventually. We can only indexed direct accessors at the moment - pure literals and variables. No different than other 5.x releases. Over time we hope to improve what can be indexed.
as well as the same using "!=".It's not possible to indexed !=
I don't understand this question as there is no join process in the RHS, and thus no possible indexing.
But the following does not permit indexing:
<any RHS expression from above> == <fieldname>
Correct?
-W
On 9 May 2011 03:55, Mark Proctor <mproctor@codehaus.org> wrote:
On 06/05/2011 07:14, Wolfgang Laun wrote:Only expressions that are equality constraints on direct fields are currently indexed.Edson,
On 6 May 2011 01:14, Edson Tirelli <ed.tirelli@gmail.com> wrote:
Wolfgang,
These are remaining bugs that must be fixed before final. Goal is to support free form expressions as long as they return a boolean value (for traditional constraints), or any value (for positional). Period.
(Well, as it's past 5.2.0M2...)
Given that any expression is valid, will there still be a distinction w.r.t. efficiency, as there was with traditional constraints as opposed to eval()? If yes, how can I tell whether a constraint expression is "good" or "bad"?
Mark
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One might assume that all legacy forms will be handled as efficiently as now, but it's possible that not only
field == ($var + 1)
but also
field == $var + 1
is efficient. Or, similarly,
field == $var
and (now) also
$var == field
But certainly not
field - 1 == $var
Or, at least, not until some later version ;-)
I repeat this quote (from 5.2.0 Drools Introduction and General User Guide) and my question, what does it mean? Where is this "documented"? Is this somehow related to the efficiency issue?
<quote>
As previously we had to document the restricted limitations of a field constraint on the LHS compared to expressions used inside of an 'eval' or used on the RHS.
</quote>
Wolfgang
Edson
2011/5/5 Wolfgang Laun <wolfgang.laun@gmail.com>
In the 5.2.0 Drools Introduction and General User Guide, there's section 2.1.3.1, Free Form expressions in Constraints (New Parser). It contains several examples:
#1 Person( age * 2 > $anotherPersonsAge + 2 )
#2 Person( addresses["home"].streetName.startsWith( "High Park" ) )
#3 Person( isAdult() )
#1 does not compile: Unable to build constraint as 'age * 2' is invalid : [Rule name='exa1']
#2 works - although I'd very much prefer not to be swamped with MVEL extensions unless I ask for it.
#3 does not compile: Unable to Analyse Expression isAdult():
[Error: no such identifier: isAdult]
[Near : {... isAdult() ....}]
Neither rule name nor line number is provided.
Would it please be possible to have a precise statement what one can write as a constraint?
<quote>
As previously we had to document the restricted limitations of a field constraint on the LHS compared to expressions used inside of an 'eval' or used on the RHS.
</quote>
I'm sorry, but I do not understand the meaning of this sentence. What does it mean, please?
Cheers
Wolfgang
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