Hi Jean-Marc, beforehand: The first issue you reported back to us recently [1] has been fixed by our functional guru Leo! A new snapshot is available [2].
> Hi. Thanks for the FLWOR trick, behaving in constant time. However it seems > to generates an unexpected 5X time overhead Most probably this is because the results of for-each will be cached, while in the previous case (if no inlining takes place), all items will be iterated. Hope this helps, Christian [1] https://github.com/BaseXdb/basex/issues/1052 [2] http://files.basex.org/releases/latest/ On Tue, Jan 13, 2015 at 9:19 AM, jean-marc Mercier <jeanmarc.merc...@gmail.com> wrote: > Christian, > > Hi. Thanks for the FLWOR trick, behaving in constant time. However it seems > to generates an unexpected 5X time overhead, and I can't use it > straightforwardly as workaround. Can you reproduce it, since this overhead > might be due to eclipse ? > > declare function local:test(){fn:for-each(1 to 10000000, > function($a){2*$a})}; > declare function local:test1(){count(local:test())}; > declare function local:test2(){let $ data := local:test() return for $n in > (1 to 10) return count($data)}; > > prof:time(local:test1()) ouput : 639.12 ms > prof:time(local:test2()) ouput : 2431.67 ms > > > > 2015-01-13 1:59 GMT+01:00 Christian Grün <christian.gr...@gmail.com>: >> >> Hi Jean-Marc, >> >> interesting one; it seems that $data is inlined and thus evaluated >> more than once. This doesn't happen if a FLWOR expression is used: >> >> let $data := fn:for-each ... >> for $n in 1 to $i >> return local:test2($data, $n) >> >> Should be easy to resolve. >> >> Thanks for your (always concise) examples, >> Christian >> >> >> On Mon, Jan 12, 2015 at 9:08 PM, jean-marc Mercier >> <jeanmarc.merc...@gmail.com> wrote: >> > Hello, >> > >> > I am facing some performances issues, probably due to unexpected query >> > reevaluation. Might it be due to the optimizer ? Here is a code to test >> > >> > declare function local:test($i){ >> > let $data := fn:for-each(1 to 10000000, function($a){2*$a} ) >> > (: let $data := xquery:eval("fn:for-each(1 to 10000000, >> > function($a){2*$a} )") :) >> > return (1 to $i) ! local:test2($data,.) >> > }; >> > >> > declare function local:test2($data, $dummy) { count($data) }; >> > >> > (1 to 10) ! prof:time(local:test(.)) >> > >> > Output : >> > >> > 683.76 ms >> > 1137.95 ms >> > 1727.68 ms >> > 2151.06 ms >> > 2694.84 ms >> > 3189.57 ms >> > 3725.1 ms >> > 4277.51 ms >> > 4815.74 ms >> > 5417.79 ms >> > >> > Note that using xquery:eval (toggling the comment inside local:test). >> > seems >> > to perform correctly. However I can't use this trick as a workaround. >> > >> > (1 to 10) ! prof:time(local:test(.)) >> > Ouput : >> > >> > 2472.71 ms >> > 825.61 ms >> > 3013.14 ms >> > 986.81 ms >> > 2982.97 ms >> > 778.24 ms >> > 1195.33 ms >> > 3280.7 ms >> > 976.96 ms >> > 913.69 ms > >
