#gStore

gStore2.0

Overview

gStore is a graph-based RDF data management system (or what is commonly called a “triple store”) that maintains the graph structure of the original RDF data. Its data model is a labeled, directed multiedge graph, where each vertex corresponds to a subject or an object. We also represent a given SPARQL query by a query graph Q. Query processing involves finding subgraph matches of Q over the RDF graph G. gStore incorporates an index over the RDF graph (called VS-tree) to speed up query processing. VS-tree is a heightbalanced tree with a number of associated pruning techniques to speed up subgraph matching.

Install Steps

System Requirement: 64-bit linux server with GCC, make installed. We have tested on linux server with CentOS 6.2 x86_64 and CentOS 6.6 x86_64. The version of GCC should be 4.4.7 or later.

You can install gStore2.0 in two commands.

1. run

# make lib_antlr

to compile and link the library we need.

2. run

# make

to compile the gStore code and build executable "gload", "gquery", "gserver", "gclient".

Usage

gStore2.0 currently includes four executables.

####1. gload gload is used to build a new database from a RDF triple format file.

# ./gload db_name rdf_triple_file_name

For example, we build a database from LUBM_10.n3 which can be found in example folder.

[root@master Gstore]# ./gload db_LUBM10 ./example/LUBM_10.n3 
2015年05月21日 星期四 20时58分21秒  -0.484698 seconds
gload...
argc: 3 DB_store:db_LUBM10      RDF_data: ./example/LUBM_10.n3  
begin encode RDF from : ./example/LUBM_10.n3 ...

####2. gquery gquery is used to query an exsisting database with SPARQL files.

#./gquery db_name

The program shows a command prompt: inputting a file name which can be interpreted as a single SPARQL query. When the program finish answering the query, it shows the command prompt again. gStore2.0 only support simple “select” queries now.

We also take LUBM_10 as an example.

[root@master Gstore]# ./gquery db_LUBM10/
gquery...
argc: 2 DB_store:db_LUBM10/
loadTree...
LRUCache initial...
LRUCache initial finish
finish loadCache
finish loadEntityID2FileLineMap
open KVstore
finish load
finish loading
please input query file path:
./example/LUBM_q0.txt
... ...
Total time used: 4ms.
final result is : 
<http://www.Department0.University0.edu/FullProfessor0>
<http://www.Department1.University0.edu/FullProfessor0>
<http://www.Department2.University0.edu/FullProfessor0>
<http://www.Department3.University0.edu/FullProfessor0>
<http://www.Department4.University0.edu/FullProfessor0>
<http://www.Department5.University0.edu/FullProfessor0>
<http://www.Department6.University0.edu/FullProfessor0>
<http://www.Department7.University0.edu/FullProfessor0>
<http://www.Department8.University0.edu/FullProfessor0>
<http://www.Department9.University0.edu/FullProfessor0>
<http://www.Department10.University0.edu/FullProfessor0>
<http://www.Department11.University0.edu/FullProfessor0>
<http://www.Department12.University0.edu/FullProfessor0>
<http://www.Department13.University0.edu/FullProfessor0>
<http://www.Department14.University0.edu/FullProfessor0>

####3. gserver gserver is a daemon. It should be launched first when accessing gStore by gclient or API. It communicates with client through socket.

[root@master Gstore]# ./gserver 
port=3305
Wait for input...

You can also assign a custom port for listening.

[root@master Gstore]# ./gserver 3307
port=3307
Wait for input...

####4. gclient gclient is designed as a client to send commands and receive feedbacks.

[root@master Gstore]# ./gclient 
ip=127.0.0.1 port=3305
->

You can also assign gserver's ip and port.

[root@centos74 Gstore]# ./gclient 172.31.19.15 3307
ip=172.31.19.15 port=3307
->

We can use these following commands now:

->import db_name rdf_triple_file_name; build a database from RDF triple file.

->load db_name; load an exsisting database.

->unload db_name; unload database, but will not delete it on disk, you can load it next time.

->query query_file_name; query the current database with a SPARQL query file.

->show datbases; show the current database's name.

->insert db_name rdf_triple_file_name; insert a handful of new RDF triples to the orginal database.

Note that each command ends with ";".

####5. API We provide JAVA and C++ API for accessing gStore now. Please refer to example codes in api/cpp/example and api/java/example.