Weird behaviour with sequence and random:integer

> ("a", "b", "c")[trace(1 + random:integer(3))]

Marco Lettere <m.lettere at gmail.com> schrieb am Mi., 22. Mai 2024, 15:34: > Dear all, > > I have this strange behavior when running in BaseX 10.4: > > ["a","b","c"](1 + random:integer(3)) > > I got something empty result, sometimes (correctly) one out of the > three, sometimes two results... > > I report the results and the trace in [1] and [2]. > > What is the reason for this? > > Thank you. > > Marco. > > [1] Two results > a > c > > Evaluating: > 1 > 3 > 3 > Compiling: > - rewrite list to xs:string sequence: ("a", "b", "c") > - swap operands: (1 + random:integer(3)) > Optimized Query: > ("a", "b", "c")[trace((random:integer(3) + 1))] > Query: > ("a", "b", "c")[trace(1 + random:integer(3))] > Result: > - Hit(s): 2 Items > - Updated: 0 Items > - Printed: 3 b > - Read Locking: (none) > - Write Locking: (none) > Timing: > - Parsing: 0.21 ms > - Compiling: 0.4 ms > - Optimizing: 0.1 ms > - Evaluating: 0.57 ms > - Printing: 0.02 ms > - Total Time: 1.31 ms > > > [2] Empty result > () > > Evaluating: > 3 > 3 > 1 > Compiling: > - rewrite list to xs:string sequence: ("a", "b", "c") > - swap operands: (1 + random:integer(3)) > Optimized Query: > ("a", "b", "c")[trace((random:integer(3) + 1))] > Query: > ("a", "b", "c")[trace(1 + random:integer(3))] > Result: > - Hit(s): 0 Items > - Updated: 0 Items > - Printed: 0 b > - Read Locking: (none) > - Write Locking: (none) > Timing: > - Parsing: 0.16 ms > - Compiling: 0.41 ms > - Optimizing: 0.15 ms > - Evaluating: 0.56 ms > - Printing: 0.02 ms > - Total Time: 1.3 ms > Query Plan: > <QueryPlan compiled="true" updating="false"> > <CachedFilter type="xs:string*"> > <StrSeq type="xs:string+" size="3"> > <Str type="xs:string" size="1">a</Str> > <Str type="xs:string" size="1">b</Str> > <Str type="xs:string" size="1">c</Str> > </StrSeq> > <FnTrace name="trace" type="xs:integer" size="1"> > <Arith op="+" type="xs:integer" size="1"> > <RandomInteger name="random:integer" type="xs:integer" size="1"> > <Int type="xs:integer" size="1">3</Int> > </RandomInteger> > <Int type="xs:integer" size="1">1</Int> > </Arith> > </FnTrace> > </CachedFilter> > </QueryPlan> > >

On 22/05/24 15:41, Christian Grün wrote: > Hi Marco, > > > ("a", "b", "c")[trace(1 + random:integer(3))] > > The filter expression is defined in such a way that the predicate is > evaluated anew for every item of the sequence. If you want > random:integer(3) to be evaluated only once, you can either bind it to > a variable… > > let $r := random:integer(3) + 1 > return ("a", "b", "c")]$r] > > …or use functions like fn:subsequence: > > subsequence(("a", "b", "c"), random:integer(3) + 1, 1) > > Hope this helps, > Christian > > > > Marco Lettere <m.lettere at gmail.com> schrieb am Mi., 22. Mai 2024, 15:34: > > Dear all, > > I have this strange behavior when running in BaseX 10.4: > > ["a","b","c"](1 + random:integer(3)) > > I got something empty result, sometimes (correctly) one out of the > three, sometimes two results... > > I report the results and the trace in [1] and [2]. > > What is the reason for this? > > Thank you. > > Marco. > > [1] Two results > a > c > > Evaluating: > 1 > 3 > 3 > Compiling: > - rewrite list to xs:string sequence: ("a", "b", "c") > - swap operands: (1 + random:integer(3)) > Optimized Query: > ("a", "b", "c")[trace((random:integer(3) + 1))] > Query: > ("a", "b", "c")[trace(1 + random:integer(3))] > Result: > - Hit(s): 2 Items > - Updated: 0 Items > - Printed: 3 b > - Read Locking: (none) > - Write Locking: (none) > Timing: > - Parsing: 0.21 ms > - Compiling: 0.4 ms > - Optimizing: 0.1 ms > - Evaluating: 0.57 ms > - Printing: 0.02 ms > - Total Time: 1.31 ms > > > [2] Empty result > () > > Evaluating: > 3 > 3 > 1 > Compiling: > - rewrite list to xs:string sequence: ("a", "b", "c") > - swap operands: (1 + random:integer(3)) > Optimized Query: > ("a", "b", "c")[trace((random:integer(3) + 1))] > Query: > ("a", "b", "c")[trace(1 + random:integer(3))] > Result: > - Hit(s): 0 Items > - Updated: 0 Items > - Printed: 0 b > - Read Locking: (none) > - Write Locking: (none) > Timing: > - Parsing: 0.16 ms > - Compiling: 0.41 ms > - Optimizing: 0.15 ms > - Evaluating: 0.56 ms > - Printing: 0.02 ms > - Total Time: 1.3 ms > Query Plan: > <QueryPlan compiled="true" updating="false"> > <CachedFilter type="xs:string*"> > <StrSeq type="xs:string+" size="3"> > <Str type="xs:string" size="1">a</Str> > <Str type="xs:string" size="1">b</Str> > <Str type="xs:string" size="1">c</Str> > </StrSeq> > <FnTrace name="trace" type="xs:integer" size="1"> > <Arith op="+" type="xs:integer" size="1"> > <RandomInteger name="random:integer" type="xs:integer" > size="1"> > <Int type="xs:integer" size="1">3</Int> > </RandomInteger> > <Int type="xs:integer" size="1">1</Int> > </Arith> > </FnTrace> > </CachedFilter> > </QueryPlan> >