Jena TDB 是否每次都将所有数据加载到内存中？

Question

我是耶拿的新手。我尝试使用 TDB 处理 Yoga 数据集。数据集大约 200M，每次我运行相同的查询，加载数据然后给出结果需要大约 5 分钟。我想知道我是否误解了 TDB 的任何部分？以下是我的代码。

String directory = "tdb";
Dataset dataset = TDBFactory.createDataset(directory);      
dataset.begin(ReadWrite.WRITE);
Model tdb = dataset.getDefaultModel();
//String source = "yagoMetaFacts.ttl";
//FileManager.get().readModel(tdb, source);
String queryString = "SELECT DISTINCT ?p WHERE { ?s ?p ?o. }";
Query query = QueryFactory.create(queryString);
try(QueryExecution qexec = QueryExecutionFactory.create(query, tdb)){
    ResultSet results = qexec.execSelect();
    ResultSetFormatter.out(System.out, results, query) ;
}
dataset.commit();    
dataset.end();

Answer 1

有两种方法可以将数据加载到tdb，通过API或CMD。非常感谢@ASKW 和@AndyS

1 通过 API

加载数据

这些代码只需要执行一次，尤其是readModel行，需要很长时间。

String directory = "tdb";
Dataset dataset = TDBFactory.createDataset(directory);      
dataset.begin(ReadWrite.WRITE);
Model tdb = dataset.getDefaultModel();
String source = "yagoMetaFacts.ttl";
FileManager.get().readModel(tdb, source);
dataset.commit(); //Important!! This is to commit the data to tdb.   
dataset.end();

数据加载到tdb后，我们可以使用如下代码进行查询。并且不需要再次加载数据。

String directory = "path\to\tdb"; 
Dataset dataset = TDBFactory.createDataset(directory);
Model tdb = dataset.getDefaultModel(); 
String queryString = "SELECT DISTINCT ?p WHERE { ?s ?p ?o. }"; 
Query query = QueryFactory.create(queryString);
try(QueryExecution qexec = QueryExecutionFactory.create(query, tdb)){
     ResultSet results = qexec.execSelect();
     ResultSetFormatter.out(System.out, results, query) ;
}

2 通过CMD加载数据

加载数据

>tdbloader --loc=path\to\tdb path\to\dataset.ttl

查询

>tdbquery --loc=path\to\tdb --query=q1.rq

q1.rq 是存储查询的文件应该得到这样的结果

-------------------------------------------------------
| p                                                   |
=======================================================
| <http://yago-knowledge.org/resource/hasGloss>       |
| <http://yago-knowledge.org/resource/occursSince>    |
| <http://yago-knowledge.org/resource/occursUntil>    |
| <http://yago-knowledge.org/resource/byTransport>    |
| <http://yago-knowledge.org/resource/hasPredecessor> |
| <http://yago-knowledge.org/resource/hasSuccessor>   |
| <http://www.w3.org/2000/01/rdf-schema#comment>      |
-------------------------------------------------------

Jena TDB 是否每次都将所有数据加载到内存中？

Does Jena TDB load all data into memory every time?

sparql

jena

tdb

1 通过 API

2 通过CMD加载数据