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query is not using attribute index with function

Friday, 30 March 2018 · 3 messages · last reply 9 Apr 2018
AW
andre weber30 Mar 2018 10:32 #
Hi, with the new Version 9 I have encountered a strange performance issue: - Running a simple xpath-query is fast, as it is using the attribute-index. Execution time: 59.19 ms - Putting the same simple xpath-query into a function results in a very poor performance. No use of the attribute-index here. Execution time: 12578.55 ms There where no issues with that in the previous Versions 8.x Here’s the setup… xquery version "3.1";
   declare function local:slow_query_here() as node()*
   {
       prof:time(
         db:open("mars","data“)/sec[ @isin = "FR0000125338" ]
       )
   (: 12578.55 ms :)
   };

   let $fast_query_here :=
       prof:time(
         db:open("mars","data“)/sec[ @isin = "FR0000125338" ]
       )
   (: 59.19 ms :)
return local:slow_query_here()
Here’s the query plan…
<QueryPlan compiled="true" updating="false">
 <GFLWOR type="element()*">
   <Let type="element()*">
     <Var name="$fast_query_here" id="0" type="element()*"/>
     <ProfTime name="time(value[,label])" type="element()*">
       <CachedPath type="element()*">
         <ValueAccess index="attribute" type="attribute()*">
           <IndexStaticDb name="mars" database="mars"/>
           <Str type="xs:string">FR0000125338</Str>
         </ValueAccess>
         <IterStep axis="self" test="*:base_isin" type="attribute()*"/>
         <CachedStep axis="parent" test="*:option" type="element()*">
           <CachedPath>
             <IterStep axis="parent" test="*:option_list" type="element()*"/>
             <IterStep axis="parent" test="*:finance" type="element()*"/>
             <IterStep axis="parent" test="document-node()" type="document-node()*"/>
           </CachedPath>
         </CachedStep>
       </CachedPath>
     </ProfTime>
   </Let>
   <ProfTime name="time(value[,label])" type="element()*">
     <CachedPath type="element()*" database="mars">
       <DBNode database="mars" pre="0" type="document-node()"/>
       <IterStep axis="descendant" test="*:option_list" type="element()*"/>
       <IterStep axis="child" test="*:option" type="element()*">
         <CmpSimpleG op="=" type="xs:boolean" size="1">
           <CachedPath type="attribute()?">
             <IterStep axis="attribute" test="*:base_isin" type="attribute()?"/>
           </CachedPath>
           <Str type="xs:string">FR0000125338</Str>
         </CmpSimpleG>
       </IterStep>
     </CachedPath>
   </ProfTime>
 </GFLWOR>
</QueryPlan>
Any idea what’s causing the performance drop? Thank you for your thoughts! Andre
CG
Christian Grün31 Mar 2018 17:10 #
Dear Andre, Thanks for your observations, which bear some similarity to what another user reported in Github [1]. I’ll get back to you soon. Best, Christian [1] https://github.com/BaseXdb/basex/issues/1553
Quoted text · andre weber · 73 lines
On Fri, Mar 30, 2018 at 10:32 AM, andre weber <atmo at gmx.de> wrote: > Hi, > > with the new Version 9 I have encountered a strange performance issue: > - Running a simple xpath-query is fast, as it is using the attribute-index. Execution time: 59.19 ms > - Putting the same simple xpath-query into a function results in a very poor performance. No use of the attribute-index here. Execution time: 12578.55 ms > > There where no issues with that in the previous Versions 8.x > > Here’s the setup… > > xquery version "3.1"; > > declare function local:slow_query_here() as node()* > { > prof:time( > db:open("mars","data“)/sec[ @isin = "FR0000125338" ] > ) > (: 12578.55 ms :) > }; > > let $fast_query_here := > prof:time( > db:open("mars","data“)/sec[ @isin = "FR0000125338" ] > ) > (: 59.19 ms :) > > return local:slow_query_here() > > > Here’s the query plan… > <QueryPlan compiled="true" updating="false"> > <GFLWOR type="element()*"> > <Let type="element()*"> > <Var name="$fast_query_here" id="0" type="element()*"/> > <ProfTime name="time(value[,label])" type="element()*"> > <CachedPath type="element()*"> > <ValueAccess index="attribute" type="attribute()*"> > <IndexStaticDb name="mars" database="mars"/> > <Str type="xs:string">FR0000125338</Str> > </ValueAccess> > <IterStep axis="self" test="*:base_isin" type="attribute()*"/> > <CachedStep axis="parent" test="*:option" type="element()*"> > <CachedPath> > <IterStep axis="parent" test="*:option_list" type="element()*"/> > <IterStep axis="parent" test="*:finance" type="element()*"/> > <IterStep axis="parent" test="document-node()" type="document-node()*"/> > </CachedPath> > </CachedStep> > </CachedPath> > </ProfTime> > </Let> > <ProfTime name="time(value[,label])" type="element()*"> > <CachedPath type="element()*" database="mars"> > <DBNode database="mars" pre="0" type="document-node()"/> > <IterStep axis="descendant" test="*:option_list" type="element()*"/> > <IterStep axis="child" test="*:option" type="element()*"> > <CmpSimpleG op="=" type="xs:boolean" size="1"> > <CachedPath type="attribute()?"> > <IterStep axis="attribute" test="*:base_isin" type="attribute()?"/> > </CachedPath> > <Str type="xs:string">FR0000125338</Str> > </CmpSimpleG> > </IterStep> > </CachedPath> > </ProfTime> > </GFLWOR> > </QueryPlan> > > Any idea what’s causing the performance drop? > > Thank you for your thoughts! > Andre
CG
Christian Grün9 Apr 2018 18:39 #
Hi Andre, The problem has been fixed [1]. A new snapshot is available [2]. BaseX 9.0.1 will probably be released around the end of April. Best, Christian [1] https://github.com/BaseXdb/basex/commit/4500547038ff69b99d04751768ac328d5276eb6d [2] http://files.basex.org/releases/latest/
Quoted text · Christian Grün · 87 lines
On Sat, Mar 31, 2018 at 5:10 PM, Christian Grün <christian.gruen at gmail.com> wrote: > Dear Andre, > > Thanks for your observations, which bear some similarity to what > another user reported in Github [1]. I’ll get back to you soon. > > Best, > Christian > > [1] https://github.com/BaseXdb/basex/issues/1553 > > > > On Fri, Mar 30, 2018 at 10:32 AM, andre weber <atmo at gmx.de> wrote: >> Hi, >> >> with the new Version 9 I have encountered a strange performance issue: >> - Running a simple xpath-query is fast, as it is using the attribute-index. Execution time: 59.19 ms >> - Putting the same simple xpath-query into a function results in a very poor performance. No use of the attribute-index here. Execution time: 12578.55 ms >> >> There where no issues with that in the previous Versions 8.x >> >> Here’s the setup… >> >> xquery version "3.1"; >> >> declare function local:slow_query_here() as node()* >> { >> prof:time( >> db:open("mars","data“)/sec[ @isin = "FR0000125338" ] >> ) >> (: 12578.55 ms :) >> }; >> >> let $fast_query_here := >> prof:time( >> db:open("mars","data“)/sec[ @isin = "FR0000125338" ] >> ) >> (: 59.19 ms :) >> >> return local:slow_query_here() >> >> >> Here’s the query plan… >> <QueryPlan compiled="true" updating="false"> >> <GFLWOR type="element()*"> >> <Let type="element()*"> >> <Var name="$fast_query_here" id="0" type="element()*"/> >> <ProfTime name="time(value[,label])" type="element()*"> >> <CachedPath type="element()*"> >> <ValueAccess index="attribute" type="attribute()*"> >> <IndexStaticDb name="mars" database="mars"/> >> <Str type="xs:string">FR0000125338</Str> >> </ValueAccess> >> <IterStep axis="self" test="*:base_isin" type="attribute()*"/> >> <CachedStep axis="parent" test="*:option" type="element()*"> >> <CachedPath> >> <IterStep axis="parent" test="*:option_list" type="element()*"/> >> <IterStep axis="parent" test="*:finance" type="element()*"/> >> <IterStep axis="parent" test="document-node()" type="document-node()*"/> >> </CachedPath> >> </CachedStep> >> </CachedPath> >> </ProfTime> >> </Let> >> <ProfTime name="time(value[,label])" type="element()*"> >> <CachedPath type="element()*" database="mars"> >> <DBNode database="mars" pre="0" type="document-node()"/> >> <IterStep axis="descendant" test="*:option_list" type="element()*"/> >> <IterStep axis="child" test="*:option" type="element()*"> >> <CmpSimpleG op="=" type="xs:boolean" size="1"> >> <CachedPath type="attribute()?"> >> <IterStep axis="attribute" test="*:base_isin" type="attribute()?"/> >> </CachedPath> >> <Str type="xs:string">FR0000125338</Str> >> </CmpSimpleG> >> </IterStep> >> </CachedPath> >> </ProfTime> >> </GFLWOR> >> </QueryPlan> >> >> Any idea what’s causing the performance drop? >> >> Thank you for your thoughts! >> Andre

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