Author: andy
Date: Mon Dec 7 15:29:10 2015
New Revision: 1718404
URL: http://svn.apache.org/viewvc?rev=1718404&view=rev
Log:
In-mem txn dataset
Added:
jena/site/trunk/content/documentation/rdf/datasets.md
Added: jena/site/trunk/content/documentation/rdf/datasets.md
URL:
http://svn.apache.org/viewvc/jena/site/trunk/content/documentation/rdf/datasets.md?rev=1718404&view=auto
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2015
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+Title: In-memory, trasnactional Dataset
+
+The in-memory, transactional dataset provides a dataset with full ACID
transaction semanticms, including abort. It provides for multiple readers and a
writer concurrently
+together with full snapshot isolation of the dataset. Readers see an
unchanging,
+consistent dataset where aggregate operations return stable results.
+
+First introduced in Jena version 3.0.1 as a beta, then in 3.1.0.
+
+During the beta phase, please log any issues with [Apache Jena
JIRA|https://issues.apache.org/jira/issues/?jql=project%20%3D%20JENA%20ORDER%20BY%20key%20DESC%2C%20priority%20DESC].
+
+## API
+
+A new instance of the class is obtained by a call to
`DatasetFactory.createTxnMem()`:
+
+ Dataset ds = DatasetFactory.createTxnMem() ;
+
+This can then be used by the application:
+
+ Dataset ds = DatasetFactory.createTxnMem() ;
+ ds.begin(READ) ;
+ try {
+ ... SPARQL query ...
+ } finally { ds.end() ; }
+
+or
+
+ Dataset ds = DatasetFactory.createTxnMem() ;
+ ds.begin(WRITE) ;
+ try {
+ ... SPARQL update ...
+ ... SPARQL query ...
+ ... SPARQL update ...
+ ds.commit() ;
+ } finally { ds.end() ; }
+
+If the application does not call `commit()`, the transaction aborts and the
changes are lost. The same happens if the application throws an exception.
+
+## Non-transactional use.
+
+If used outside of a transaction, the implementation proiveds auto-commit
functionality. Each triple or added or deleted is done inside an implicit
transaction. This can lead to
+measurable slow down. It is better to do a group of operations inside a single
transaction
+explicitly in the application code.
+
+## Assembler
+
+The assembler provies for the creation of a dataset and also loading it with
data read from URLs (files or from any other URL).
+
+* Type: `ja:MemoryDataset`
+
+* Properties:
+ * `ja:data` <i>`urlForData`</i>
+ * `ja:pNamedGraph`, for loading a specific graph of the dataset.
+ This uses `ja:graphName` to specific the name and `ja:data` to load data.
+
+The examples use the following prefixes:
+
+ @prefix ja: <http://jena.hpl.hp.com/2005/11/Assembler#> .
+ @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+
+To create an empty in-memory dataset, all that is required is the line:
+
+ [] rdf:type ja:MemoryDataset .
+
+With triples for the default graph, from file "dataFile.ttl", Turtle format.
+
+ [] rdf:type ja:MemoryDataset ;
+ ja:data <file:dataFile.ttl> .
+
+With triples from several files
+
+ [] rdf:type ja:MemoryDataset ;
+ ja:data <file:data1.ttl> ;
+ ja:data <file:data2.nt> ;
+ ja:data <file:data3.jsonld> ;
+ .
+
+Load TriG:
+
+ [] rdf:type ja:MemoryDataset ;
+ ja:data <file:data.trig> .
+
+Load a file of triples, put into a named graph.
+
+ [] rdf:type ja:MemoryDataset ;
+ ja:namedGraph [ ja:graphName <http://example/graph> ; ja:data
<file:///fullPath/data.ttl> ] .
