Dear Christian, Tested the snapshot yesterday, and now the expression works as expected. Thank you. Do you have a target date for the release of BaseX 9.3? Best regards, Johannes -----Ursprüngliche Nachricht----- Von: Christian Grün [mailto:christian.gruen@gmail.com] Gesendet: Donnerstag, 24. Oktober 2019 12:41 An: Johannes Echterhoff <echterhoff@interactive-instruments.de> Cc: BaseX <basex-talk@mailman.uni-konstanz.de> Betreff: Re: [basex-talk] Optimization issue? Dear Johannes, Thanks for the reproducible test case. The bug (a too eager merge of combined range expressions) was fixed and a new snapshot is available [1,2]. Cheers Christian [1] https://github.com/BaseXdb/basex/issues/1744 [2] http://files.basex.org/releases/latest/ On Thu, Oct 24, 2019 at 10:54 AM Johannes Echterhoff <echterhoff@interactive-instruments.de> wrote:
Hello,
I’m experiencing some strange behavior when executing the following query in the BaseX 9.2.4 GUI (nevermind the awkward query structure – that is just to be able to inspect the results of the individual evaluation steps):
let $t := <x>200.0000</x>
let $num := number($t)
let $gt5000 := $num gt 5000
let $ltMinus5000 := $num lt -5000
return $gt5000 or $ltMinus5000
The result is true, although it should be false.
The compilation and optimization logs for this query in the GUI tell us the following:
----------
Compiling:
- rewrite > comparison to range comparison: ($num_1 > 5000) -> ($num_1
= 5000.000000000001)
- rewrite 'gt' comparison to range comparison: ($num_1 gt 5000) -> ($num_1 >= 5000.000000000001)
- pre-evaluate unary expression to xs:integer item: -5000
- rewrite < comparison to range comparison: ($num_1 < -5000) -> ($num_1 <= -5000.000000000001)
- rewrite 'lt' comparison to range comparison: ($num_1 lt -5000) -> ($num_1 <= -5000.000000000001)
- inline $gt5000_2
- inline $ltMinus5000_3
- simplify or: (true())
- pre-evaluate or to xs:boolean item: (true()) -> true()
- remove unused variable $num_1
- remove unused variable $t_0
- simplify FLWOR expression: true()
Optimized Query:
true()
----------
When the return statement is changed to “return ($num,$gt5000,$ltMinus5000,$gt5000 or $ltMinus5000)” then the result of the boolean operation (last element of the result sequence) is false, as expected.
The GUI log then is:
----------
Compiling:
- rewrite > comparison to range comparison: ($num_1 > 5000) -> ($num_1
= 5000.000000000001)
- rewrite 'gt' comparison to range comparison: ($num_1 gt 5000) -> ($num_1 >= 5000.000000000001)
- pre-evaluate unary expression to xs:integer item: -5000
- rewrite < comparison to range comparison: ($num_1 < -5000) -> ($num_1 <= -5000.000000000001)
- rewrite 'lt' comparison to range comparison: ($num_1 lt -5000) -> ($num_1 <= -5000.000000000001)
Optimized Query:
let $t_0 := element x { ("200.0000") } let $num_1 := number($t_0) let $gt5000_2 := ($num_1 >= 5000.000000000001) let $ltMinus5000_3 := ($num_1 <= -5000.000000000001) return ($num_1, $gt5000_2, $ltMinus5000_3, ($gt5000_2 or $ltMinus5000_3))
----------
Am I missing something, or could this be a bug in BaseX 9.2.4? With BaseX 9.0.2, both queries (with the different return statements) returned the expected value false for the boolean operation.
Best regards,
Johannes