In addition to previous query. It is taking a lot of time to first parse the
dataset using NXParser then checking for object, and creating quad again and
storing in TDB. It could be very simple if we can take the quad check its
object and insert it in TDB.
But Jena is not helping me with this 😞
So I have to create quads again and store it in TDB.
Any help is surely appreciated.
Regards,
Samita Bai
________________________________
From: Samita Bai / PhD CS Scholar @ City Campus
Sent: 16 April 2018 13:33:51
To: users@jena.apache.org
Subject: Re: TDB 2 Store Parameters
Thank you Andy and Adam for the help. Actually, I am just indexing the quads
where object is either literal or foreign URI (i.e. Object belonging to
different dataset than subject), I am using NXParser (as Jena is giving various
parsing errors) to parse the dataset and then I am storing in TDB2 in the
following manner.
public void SetQuadsList(String sub, String pred, String obj, String context) {
Node subjects = NodeFactory.createURI(sub);
Node objects = NodeFactory.createURI(obj);
Node contexts =NodeFactory.createURI(context);
//Node rdfSeeAlso = RDFS.seeAlso.asNode();
Node predicates =NodeFactory.createURI(pred);
//Quad quads = Quad.create(contexts, objects, rdfSeeAlso, subjects);
Quad quads = Quad.create(contexts, subjects, predicates, objects);
QuadList.add(quads);
//System.out.println("Number of backlinks:" + QuadList.size());
//System.out.println("quad written");
//System.out.println("Quad"+quads.toString());
}
public List<Quad> GetQuadsList(){
return QuadList;
}
public void QuadsToTDB(List<Quad> quadList) {
final String DATASET_DIR_NAME = "DyLDO1000K_Index";
Dataset dataset = TDB2Factory.connectDataset ( DATASET_DIR_NAME );
dataset.begin ( ReadWrite.WRITE );
try {
DatasetGraph dsg = dataset.asDatasetGraph();
Iterator<Quad> quads = quadList.iterator();
System.out.println("Size of Quad List: "+quadList.size());
while ( quads.hasNext() ) {
//System.out.println("here");
Quad quad = quads.next();
dsg.add(quad);
//System.out.println(quad.toString()+ "added");
//RDFDataMgr.writeQuads(System.out, quads);
// RDFDataMgr.write(System.out, dsg, Lang.NQUADS);
}
System.out.println("dsg created of size "+dsg.size());
//RDFDataMgr.write(System.out, dsg, Lang.NQUADS);
System.out.println("written dsg using datamgr.");
//System.out.println(dataset.isEmpty());
//RDFDataMgr.write(System.out, dsg, Lang.NQUADS);
dataset.commit();
System.out.println("committed dataset.");
} catch ( Exception e ) {
e.printStackTrace(System.err);
//dataset.abort();
} finally {
//RDFDataMgr.write(System.out, dsg, Lang.NQUADS);
dataset.end();
}
System.out.println("end method.");
}}
I have indexed 40,000 files (as I have spilited the dataset into files
according to context) and the index size has become 120 GB. I have a total of
1,35,600 files whose total size is 19.8 GB only.
Why the TDB is making such BIG index size. I am confused :( is there any
problem in my code.
Please suggest me if there can be some improvements.
Regards,
Samita Bai
________________________________
From: ajs6f <aj...@apache.org>
Sent: 15 April 2018 03:07:59
To: users@jena.apache.org
Subject: Re: TDB 2 Store Parameters
42 million quads is nothing like so many that either TDB version should have
any problem doing normal indexing (assuming very little in the way of
hardware-- I ingest datasets like that on my laptop all the time).
Do you have some extraordinary hardware limitations?
Adam
> On Apr 14, 2018, at 11:42 AM, Andy Seaborne <a...@apache.org> wrote:
>
> Hi Samita,
>
> Firstly - as Adam points out - if theer are no indexes then access to the
> data will be very slow. For a GSPO index, that means squeries must be
> "GRAPH <uri> { ... }" and probably "GRAPH <uri> { <fixedSubject>.. }".
>
> GSPO means lookup by G then S within those G and the same for P then O.
>
> I looked at the data and it seems to be able 42 million quads.
>
> Using TDB1 (the loader is faster at this scale currently) is likely to be a
> better choice.
>
> Looking at StoreParams in TDB2:
>
> The code below creates the database at TDB2Factory.connectDataset so any
> StoreParams after that do not affect indexing.
>
> I tried to make it work in the release but the code ignores provided
> StoreParams - sorry. Even if it did work, it hits a test to make sure there
> are basic indexing (Adam's point).
>
> Andy
>
>
> On 13/04/18 13:42, Samita Bai / PhD CS Scholar @ City Campus wrote:
>> I wrote the following code to build only one type of triple and quad index
>> but it is still creating all indexes 😞
>> package ldbqPack;
>> import org.apache.jena.query.Dataset;
>> import org.apache.jena.tdb2.TDB2Factory;
>> import org.apache.jena.tdb2.setup.StoreParams;
>> import org.apache.jena.tdb2.sys.DatabaseConnection;
>> import org.apache.jena.dboe.base.block.FileMode;
>> import org.apache.jena.dboe.base.file.Location;
>> import org.apache.jena.tdb2.setup.StoreParamsFactory;
>> public class StrPrms {
>> static String[] tindexes= {"SPO"};
>> static String[] qindexes= {"GSPO"};
>> static String[] pindexes= {"GPU"};
>> static final StoreParams pApp = StoreParams.builder()
>> .blockSize(12) // Not dynamic
>> .nodeMissCacheSize(12) // Dynamic
>> .build();
>> static final StoreParams pLoc = StoreParams.builder()
>> .blockSize(0)
>> .nodeMissCacheSize(0).build();
>> static final StoreParams pDft = StoreParams.builder()
>> .fileMode(FileMode.mapped)
>> .blockSize(8192)
>> .blockReadCacheSize(5000)
>> .blockWriteCacheSize(1000)
>> .node2NodeIdCacheSize(200000)
>> .nodeId2NodeCacheSize(750000)
>> .nodeMissCacheSize(1000)
>> .nodeTableBaseName("nodes")
>> .primaryIndexTriples("SPO")
>> .tripleIndexes(tindexes)
>> .primaryIndexQuads("GSPO")
>> .quadIndexes(qindexes)
>> .prefixTableBaseName("prefixes")
>> .primaryIndexPrefix("GPU")
>> .prefixIndexes(pindexes)
>> .build();
>> public static void main(String[] args) {
>> // TODO Auto-generated method stub
>> final String DATASET_DIR_NAME = "DyLDO100";
>> Dataset dataset = TDB2Factory.connectDataset ( DATASET_DIR_NAME );
>> Location location = Location.create(DATASET_DIR_NAME);
>> StoreParams custom_params =
>> StoreParamsFactory.decideStoreParams(location, true, pApp, pLoc, pDft);
>> DatabaseConnection.connectCreate(location, custom_params);
>> StoreParams params = StoreParams.getSmallStoreParams();
>> System.out.println(params);
>> }
>> }
>> Please help.
>> Regards,
>> Samita Bai
>> ________________________________
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________________________________
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contain confidential and privileged information. If you are not the intended
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