Graph Database for Collaborative Communities - Community-Built Databases: Research and Development - page 214

objects. Path objects are objects with an additional list of references to simple and
link objects that form a path over the database graph. GraphDB uses graph algo-
rithms in order to implement graph operations. Both the shortest path and cycle
were implemented using the A* algorithm. Moreover, nodes, paths, and subgraphs
are indexed using path classes and index structures such as B-Tree and LSD-Tree.
GraphDB allows aggregation by using aggregate functions.
GOQL
GOQL [ 21 ] is an extension of OQL enriched with constructs to create, manipulate
and query objects of type graph, path, and edge. GOQL is applied to graph
databases that use an object-oriented data model. In this data model, they define,
similar to GraphDB, a special type: node type, edge type, path type, and graph type.
GOQL is capable to query sequences and paths. In addition to the OQL sequence
operators, GOQL uses the temporal operators Next, Until, and Connected for queries
involving the relative ordering of sequence elements. For processing, GOQL
queries are translated into an operator-based language, O-Algebra, extended with
new operators. O-Algebra is an object algebra designed for processing object-
oriented database (OODB) queries. To deal with GOQL's extension for path and
sequence expressions, O-Algebra is extended with three temporal operators,
corresponding to the temporal operators: Next, Until and Connected.
SOQL
SOcial networks Query Language (SoQL) [ 22 ] is an SQL-like language for query-
ing and creating data in social networks. SoQL enables the user to retrieve paths to
other participants in the network and to use a retrieved path in order to attempt to
create a connection with the participant at the end of the path. The main element of
a SoQL query is either a path or a group, with subpaths, subgroups, and paths within
a group defined in the query. Creation of new data is also based on the path and
group structures. Indeed, SoQL presents four new operators:
- SELECT FROM PATH query which retrieves paths between network partici-
pants, starting at a specific node and satisfying conditions in the path predicates.
- SELECT FROM GROUP query which retrieves groups of participants that
satisfy conditions as a set of nodes.
- The CONNECT USING PATH and CONNECT GROUP commands are pre-
sented. These commands automate the process of creating connections between
participants.
The language uses operators that specify conditions on a path or a group. It also
proposes aggregation functionalities, as well as existential and universal quantifiers
on nodes and edges in a path or a group, and on paths within a defined group.