Combining sparql queries to speed up the calling process ?

[jaanam]

Hello,

I have the two queries below which I run from my code so that the 1st 
query returns about 3000  ?ng and ?t_id pairs which will then be used in 
the second query in the place of $STAT and $RDF_ID. So I'm calling the 
second query in a loop about 3000 times.

I've noticed that it is time consuming; it takes about 4-5 minutes. How 
could I combine the queries so that I could get all the information by 
just one call ?

$PREFIXS
    SELECT *
    WHERE
          {
              {
                   GRAPH stat:outputchannel
                        {
                            ?subject outchl:refersToTable ?t_id .
                            ?subject outchl:refersToNamedGraph ?ng .
                            ?subject outchl:hasOutputFileId ?o_id.
                            filter (regex(?o_id,"of_001"))
                        }
                }
           }


and

$PREFIXS

   SELECT *
   FROM stat:outputchannel
   FROM stat:tabAdmin
   FROM tilasto:$STAT
   WHERE {
         ?pxfile pxt:tableId "$RDF_ID".
         ?pxfile pxt:hasStatus ?status.
         ?pxfile pxt:hasFrequency ?frequency.
         ?pxfile pxt:isPresentationOf ?cube.
         ?cube dc:description ?title_fi.
         ?cube dc:language ?language.
         ?cube cubemeta:hasStatisticalProgramme ?statisticalProgram.
         ?cube cubemeta:lastUpdated ?lastUpdated.
         ?cube cubemeta:refersToOutputFile ?of.
         ?subject outchl:hasOutputFileId ?of.
         ?subject outchl:refersToOutputChannel ?channel_prefix .
         ?kanta outchl:hasOutputChannelId ?channel_prefix .
         ?kanta outchl:directoryPathRoot ?directoryPathRoot .
         ?kanta a outchl_ont:OutputChannel .
         filter(?language ="fi"^^xsd:language)
         filter (lang(?title_fi) = "fi")
         filter ( langMatches(lang(?directoryPathRoot),"fi") )
}

Br jaana M