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## Survey of Graph Database Models

**RENZO ANGLES and CLAUDIO GUTIERREZ**

**Computer Science Department, Universidad de Chile**

**2. GRAPH DATA MODELING**

a graph db-model is characterized by:

**The data and/or the schema are represented by graphs**, or by data structures generalizing the notion of graph (hypergraphs or hypernodes).

- The approach is to model the database directly and entirely as a graph [G¨uting 1994].
- A graph db-model is one whose single underlying data structure is a labeled directed graph; the database consists of a single digraph [Levene and Loizou 1995].
- A database schema in this model is a directed graph, where leaves represent data and internal nodes represent connections between the data [Kuper and Vardi 1984].
- Directed labeled graphs are used as the formalism to specify and represent database schemas, instances, and rules [Paredaens et al. 1995].
- In this model, a database is described in terms of a labeled directed graph called schema graph [Kunii 1987].
- A graph db-model formalizes the representation of the data structures stored in the databases as a graph [Graves et al. 1995a].
- The schema as well as the instance of an object database is represented by a graph. The nodes of the instance represent the objects of the database [Gyssens et al. 1990].
- Database instances and database schemas are described by certain types of labeled graphs [Hidders 2002].
- The model for data is organized as graphs [Amann and Scholl 1992]. Labeled graphs are used to represent schemas and instances [Hidders and Paredaens 1993].

**Data manipulation is expressed by graph transformations [Gyssens et al. ****1990], **or by operations whose main primitives address directly typical features of graphs, like paths, neighborhoods, subgraphs, graph patterns, connectivity, and statistics about graphs (diameter, centrality, etc.)

**A.12 Related Data Models**