java - Write to Jena RDF model through pagination -

i intend convert data in sql database rdf dump. have model , ontology defined.

model model = modelfactory.createdefaultmodel(); ontmodel ontmodel = modelfactory.createontologymodel(ontmodelspec.owl_dl_mem, model); 

the ontmodel has many classes defined in it. let suppose have 10000 records in sql db , want load them model , write file. however, want paginate in case of memory overflow.

int fromindex = 0; int toindex = 10;  while(true) {      //1. resources between fromindex toindex sql db      // if no more resources 'break'      //2. push these resources in model                         //3. write model file      rdfwriter writer = model.getwriter();      file file = new file(file_path);      filewriter filewriter = new filewriter(file, true);      writer.write(this.model, filewriter, base_url);       model.close();       = to+1;      = to+10;               }   

now, how 1 append new resources existing resources in file. because see ontology getting written twice , throws exception

org.apache.jena.riot.riotexception: markup in document following root element must well-formed.

is there way handle already?

now, how 1 append new resources existing resources in file. because see ontology getting written twice , throws exception

a model set of triples. can add more triples set, that's not quite same thing "appending", since model doesn't contain duplicate triples, , sets don't have specified order, "appending" isn't quite right metaphor.

jena can handle pretty big models, might first see whether can create model , add it, , write model file. while it's cautious, it's not bad idea see whether can want without jumping through hoops.

if have problems in-memory models, might consider using tdb backed model use disk storage. incremental updates model using model api, or sparql queries, , extract model afterward in serialization.

one more option, , easiest if want append file, use non-xml serialization of rdf, such turtle or n-triples. these text based (n-triples line-based), appending new content file not problem. approach described in answer adding more individuals existing rdf ontology.