> A typical graph dbms exposes a node selection (often only allowing to start at a single entry node or selecting a set of nodes by tags) and arc selection / filtering.
That doesn't contradict my view. In fact, I'd argue that it counts, due to the fact that graph operations are provided.
> None of such databases ever featured a query language capable of defining a Dijkstra algorithm.
Most modern graph databases do seem to feature some sort of query language. I won't argue that it's strictly necessary, as long as you have well-suited, well-defined operations on graphs. I can't speak to Dijkstra's algorithm -- that was a part of the thread that I overlooked previously.
> And, no, for a typical use of a graph database, it matters most how cheap it is to follow a graph arc. Therefore, representation matters. Otherwise a graph interface on top of a relational storage would have been sufficient.
I don't mean to imply that choice of data layout/representation doesn't matter at all, but that it doesn't matter for the purpose of deciding what constitutes a graph and distinguishing graphs from non-graph objects. Of course, as with any ADT, there are various trade-offs that need to be considered before deciding on a particular memory layout.
That doesn't contradict my view. In fact, I'd argue that it counts, due to the fact that graph operations are provided.
> None of such databases ever featured a query language capable of defining a Dijkstra algorithm.
Most modern graph databases do seem to feature some sort of query language. I won't argue that it's strictly necessary, as long as you have well-suited, well-defined operations on graphs. I can't speak to Dijkstra's algorithm -- that was a part of the thread that I overlooked previously.
> And, no, for a typical use of a graph database, it matters most how cheap it is to follow a graph arc. Therefore, representation matters. Otherwise a graph interface on top of a relational storage would have been sufficient.
I don't mean to imply that choice of data layout/representation doesn't matter at all, but that it doesn't matter for the purpose of deciding what constitutes a graph and distinguishing graphs from non-graph objects. Of course, as with any ADT, there are various trade-offs that need to be considered before deciding on a particular memory layout.