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Posted to users@jena.apache.org by Eric Scott <er...@att.net> on 2020/11/23 14:41:41 UTC

Guidance on configuring TDB stores with assembler files

<https://crosschx.slack.com/archives/D01BC93UUCS/p1606141163002200>Hi all-

I'm hoping to be able to use assembler files to maintain a library of 
resources that can later be indexed into TDB2, but I think there's 
something I'm not getting.

See the appendix below for my minimal config file.

It's my understanding that I should be able to do this:

Dataset ds = TDB2Factory.assembleDataset("path/to/mini-config.ttl") ;

Then run this query against ds:

Select * where {?s ?p ?o.}

And get the triple I encoded with a literalContent statement.

When I run this, the assembleDataset operation does indeed construct the 
tdb repo at the indicated location, but the query returns nothing.Is 
there some extra step I need to do that I'm missing?

Thanks,


# APPENDIX:mini-config.ttl

@prefix tdb: <http://jena.apache.org/2016/tdb#>
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix ja: <http://jena.hpl.hp.com/2005/11/Assembler#> .

[] ja:loadClass "org.apache.jena.tdb2.TDB2" .
tdb:DatasetTDB2 rdfs:subClassOf ja:RDFDataset .
tdb:GraphTDB2    rdfs:subClassOf  ja:Model .

<#MyTDBDataset> a tdb:DatasetTDB2;
     tdb:location "DB" ;
     .

<#MyGraph> a tdb:GraphTDB2;
     rdfs:comment "A graph with a single triple" ;
     tdb:dataset <#MyTDBDataset>;
     ja:content [ja:literalContent "<http://eg.com/a> <http://eg.com/b> 
<http://eg.com/c>."] ;
     .

Re: Guidance on configuring TDB stores with assembler files

Posted by Andy Seaborne <an...@apache.org>.
Hi Eric,

 > <#MyGraph> a tdb:GraphTDB2;
 >      rdfs:comment "A graph with a single triple" ;
 >      tdb:dataset <#MyTDBDataset>;
 >      ja:content [ja:literalContent
 >          "<http://eg.com/a> <http://eg.com/b> <http://eg.com/c>."
 >      ] ;


tdb:GraphTDB2 does not support ja:content

The assembler file is going to be used every time the application runs, 
whereas data is "load once"; it would not know if the data has 
previously been load or not.

You can load data before hand:

tdb2.tdbloader --loc "DB"

even from a pipe:

echo "<http://eg.com/a> <http://eg.com/b> <http://eg.com/c>." | \
   tdb2.tdbloader --loc DB2

     Andy


On 23/11/2020 14:41, Eric Scott wrote:
> <https://crosschx.slack.com/archives/D01BC93UUCS/p1606141163002200>Hi all-
> 
> I'm hoping to be able to use assembler files to maintain a library of 
> resources that can later be indexed into TDB2, but I think there's 
> something I'm not getting.
> 
> See the appendix below for my minimal config file.
> 
> It's my understanding that I should be able to do this:
> 
> Dataset ds = TDB2Factory.assembleDataset("path/to/mini-config.ttl") ;
> 
> Then run this query against ds:
> 
> Select * where {?s ?p ?o.}
> 
> And get the triple I encoded with a literalContent statement.
> 
> When I run this, the assembleDataset operation does indeed construct the 
> tdb repo at the indicated location, but the query returns nothing.Is 
> there some extra step I need to do that I'm missing?
> 
> Thanks,
> 
> 
> # APPENDIX:mini-config.ttl
> 
> @prefix tdb: <http://jena.apache.org/2016/tdb#>
> @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
> @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
> @prefix ja: <http://jena.hpl.hp.com/2005/11/Assembler#> .
> 
> [] ja:loadClass "org.apache.jena.tdb2.TDB2" .
> tdb:DatasetTDB2 rdfs:subClassOf ja:RDFDataset .
> tdb:GraphTDB2    rdfs:subClassOf  ja:Model .
> 
> <#MyTDBDataset> a tdb:DatasetTDB2;
>      tdb:location "DB" ;
>      .
> 
> <#MyGraph> a tdb:GraphTDB2;
>      rdfs:comment "A graph with a single triple" ;
>      tdb:dataset <#MyTDBDataset>;
>      ja:content [ja:literalContent "<http://eg.com/a> <http://eg.com/b> 
> <http://eg.com/c>."] ;
>      .
> 
> 
>