[MarkLogic Dev General] weird xpath behaviour

[Szabolcs Illes]

Hi,

 

I have seen this before, but came across again, so I thought ask this
time. Same/similar xquery but different results:

 

Version 1:

 

let $ids := /HorseRacingCard/Meeting[@country eq "England" and
AdvancedGoing]/@id 

return (/HorseRacing/Meeting[@id = $ids] )[1]

 

returns expected results.

 

Version 2: Same as 1 but ids vatriable is just inlined

 

(/HorseRacing/Meeting[@id = /HorseRacingCard/Meeting[@country eq
"England" and AdvancedGoing]/@id ] )[1]

 

returns nothing [ slow, but that's expected: ]

 

Other than Version 2 is NOT optimal since the expression inside the
predicate is evaluated for each sequence item, I guess it should return
the same results. 

 

Version 3:

(/HorseRacing/Meeting[@id =
fn:collection()/HorseRacingCard/Meeting[@country eq "England" and
AdvancedGoing]/@id ] )[1]

 

Returns expected results and it's fast, expression is only evaluated
once

 

Can someone shed some light why Version 2 is not returning any results?
Could it be a bug in the optimizer? 

 

Thanks,

Szabolcs

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