Andy, ok, so the group insertion is a different query, but even if that is the case, why can the FILTER assignment not take place in all groups?
Note that in 2.6.x, something along these lines did happen (I don't have the plan around, but we because of our performance numbers) Simon From: Andy Seaborne <[email protected]> To: Simon Helsen/Toronto/IBM@IBMCA Cc: [email protected] Date: 07/18/2012 05:42 PM Subject: Re: optimization opportunity lost in 2.7.x which existed in 2.6.x? On 18/07/12 16:25, Simon Helsen wrote: > Andy, > > I have simplified the scenario a little bit. So the following query > > PREFIX p1:<t1> > PREFIX p2:<t2> > SELECT DISTINCT ?R1 ?optionalValue > WHERE > { > ?R1 p1:pr1 <https://host:9443/jts/process/project-areas/p> > FILTER ( ?R1 = <https://host:9443/rm/resources/_r1>) > OPTIONAL > { ?R1 p2:pr2 ?optionalValue } > } > > leads to > > (prefix ((p1: <file:///C:/Temp/t1>) > (p2: <file:///C:/Temp/t2>)) > (distinct > (project (?R1 ?optionalValue) > (filter (= ?R1 <https://host:9443/rm/resources/_r1>) > (conditional > (bgp (triple ?R1 p1:pr1 > <https://host:9443/jts/process/project-areas/p>)) > (bgp (triple ?R1 p2:pr2 ?optionalValue))))))) > > whereas the following query > > PREFIX p1:<t1> > PREFIX p2:<t2> > SELECT DISTINCT ?R1 ?optionalValue > WHERE > { > { > ?R1 p1:pr1 <https://host:9443/jts/process/project-areas/p> > FILTER ( ?R1 = <https://host:9443/rm/resources/_r1>) > } > OPTIONAL > { ?R1 p2:pr2 ?optionalValue } > } > > leads to > > (prefix ((p1: <file:///C:/Temp/t1>) > (p2: <file:///C:/Temp/t2>)) > (distinct > (project (?R1 ?optionalValue) > (conditional > (assign ((?R1 <https://host:9443/rm/resources/_r1>)) > (bgp (triple <https:/host:9443/rm/resources/_r1> p1:pr1 > <https://perfjts.ibm.com:9443/jts/process/project-areas/p>))) > (bgp (triple ?R1 p2:pr2 ?optionalValue)))))) > > So, looking at this in more detail, the former plan surprises me a bit > because it proposes to evaluate p1:pr1 as optional, even though I didn't > express that in the query. Yes, you did. "conditional" is a binary operator, an optimized for of leftjoin. The first arg is the fixed side and the second args the conditional part. { ?s ?p ?o OPTIONAL { ?s1 ?p1 ?o1 } } becomes (leftjoin (bgp (triple ?s ?p ?o) (bgp (triple ?s1 ?p1 ?o1)) which is executed as (conditional (bgp (triple ?s ?p ?o) (bgp (triple ?s1 ?p1 ?o1)) (sequence) is rather different. > WHERE > { > { > ?R1 p1:pr1 <https://host:9443/jts/process/project-areas/p> > FILTER ( ?R1 = <https://host:9443/rm/resources/_r1>) > } > OPTIONAL > { ?R1 p2:pr2 ?optionalValue } > } is a different query because FILTERS are group-wide, a group being what is between {} (caveat a special case in OPTIONAL not occuring here). Adding the extra {} means the FILTER is applied to ?R1 p1:pr1 <https://host:9443/jts/process/project-areas/p> alone. Andy
