Re: Combining sparql queries to speed up the calling process ?

[Andy Seaborne]

On 04/05/2023 07:18, jaa...@kolumbus.fi wrote:
Andy Seaborne kirjoitti 4.5.2023 00:24:
Do you have to use FROM in the second query?

I don't know how to present it because in the 2nd query I'm querying 
three named graphs, where the third one ($STAT) should be replaced with 
the result of the 1st query (?ng)


But do you need a merged graph or can you use GRAPH? FROM of multiple 
graphs may be a significant cost.  (It precludes TDB executing more 
directly on basic graph patterns.)

With GRAPH ?g you can apply a condition to the ?g.
And that means you can combine the queries which might help - to know, 
needs an experiment.

---

3000 queries in 5 mins is 100ms a query, including client and server 
overheads.

Are you doing the 3000 queries in parallel? A bit of parallelism might 
save elapsed time (start with parallel = 2).

    Andy

Br, Jaana


On 03/05/2023 17:58, jaa...@kolumbus.fi wrote:
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