See the following response to this issue on the OpenLink Community Forum
https://community.openlinksw.com/t/sparql-slow-if-more-object-value-specified/2064/2
... post all further questions there ...
> On 26 Oct 2020, at 04:49, William Kisman wrote:
>
> Hi , I am using virtuoso 7 open source edition,
>
> This query below is fast, it return the result instantly,
>
> select *
> WHERE {
>
> graph > {
>
> ?catAtt qq:catId ?catId;
> qq:caDataType ?caDataType;
> qq:showInView ?showInview;
> qq:valFormat?valFormatKey;
> qq:multiple ?multiple;
> qq:position ?position;
> qq:link ?link;
> qq:catAttName ?catAttName;
> qq:setting ?setting;
> qq:flag ?flag;
> qq:unit ?caUnit.
>
>
>
>
> }
> }
>
>
> LIMIT 20
> This query is so slow, took 10 seconds for the result, the only difference is
> the ?catId is replaced with literal value 1 . I thought this should be faster
> because it's more specific.
>
> select *
> WHERE {
>
> graph > {
>
> ?catAtt qq:catId 1;
> qq:caDataType ?caDataType;
> qq:showInView ?showInview;
> qq:valFormat?valFormatKey;
> qq:multiple ?multiple;
> qq:position ?position;
> qq:link ?link;
> qq:catAttName ?catAttName;
> qq:setting ?setting;
> qq:flag ?flag;
> qq:unit ?caUnit.
>
>
>
>
> }
> }
>
>
> LIMIT 20
> Why is it so ? I am still new to sparql and triplestore, seems like I have to
> do some indexing on the object ?
>
> I have tried creating the GOPS index with, I don't understand about the
> Partition part, is using O correct ? What does that partition mean ? Creating
> this index has improved the execution for the second query to 4 seconds, but
> still too slow for a DBMS.
>
> CREATE COLUMN INDEX RDF_QUAD_GOPS
> ON RDF_QUAD (G, O, P, S)
> PARTITION (O VARCHAR (-1, 0hex));
>
> Btw, does virtuoso stored triplet in the regular RDBMS table ? in the table
> DB.DBA.RDF_QUAD ? So virtuoso does not have a native storage of graph ? Or
> what I don't understand ?
>
> Thanks
> Best regards,
>
> William
>
>
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