petern's comments

petern | 12 years ago | on: Neo4j 2.0 GA - Graphs for Everyone

They are used to attache indexes and constraints on them in order to speed up traversals. They themselves have very little logic right now, more will follow in terms of query optimisation etc..

petern | 13 years ago | on: Titan: A Highly Scalable, Distributed Graph Database

Yes, all information models are basically isomorphic. However, Neo4j for instance maintains referential integrity along the relationships, making sure there will never be a relationships without start- or endnode. In a K/V store or document store, there are no guarantees that your IDs pointing to other objects are updated as you change, delete or move the target data. Also, the graph structure is maintained on dics, meaning you can direct pointers on the storage level even in non-cached scenarios, while in a K/V or Document store you need to recreate the graph in memory before being able to do anything with it.

As for special indexes and queries, look at things like http://docs.neo4j.org/chunked/snapshot/cypher-query-lang.htm... expressing patterns and walks in graphs.

You can combine index lookups in e.g. Redis, MongoDB or Lucene with the core graph engine.

See http://docs.neo4j.org/chunked/snapshot/index.html for docs.

/peter

petern | 16 years ago | on: No to SQL? Anti-database movement gains steam

Fully agree. look at graph databases like Neo4j, which has ACID semantics but no SQL interface. Then, IMHO SQL is not only geared towards a special RDBMS type of underlying database but even against a special problem domain that is not always applicable, leading to query languages like SparQL.
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