[DISCUSS]Delete an Vertex

[zlcook]

• Delete a vertex:

DELETE VERTEX vid

graph layer need send three requests to delete a vertex:

1. First request, get all edgeKeys(out-edges and in-edges) of the vertex needed te be deleted.
2. Second request, delete the all edges of the vertex accroding to the edgeKeys.
3. Finally, delete the vertex

• parser
• executor and tests in graphd

[whitewum]

1. first delete the surrounding edges then delete the vertex (in case of hangling edges)
2. when deleting a huge vertex ( a lot of in and out edges), the deleting process will be very very long (and may fail).
3. I'd prefer not to save the process in meta-server, and not to provide operation transactions, just let graph-client to check the result (e.g., double vertex delete).
4. maybe hangling edge is also an available option, let user make the choice when deleting.

[sherman-the-tank]

Please DO NOT use Chinese punctuation

[zlcook]

Done