DSE Graph Queries

Use Session.execute_graph() or Session.execute_graph_async() for executing gremlin queries in DSE Graph. The DSE driver defines three Execution Profiles suitable for graph execution:

See Getting Started and Execution Profile documentation for more detail on working with profiles.

The DSE driver executes graph queries over the Cassandra native protocol:

from dse.cluster import Cluster, GraphExecutionProfile, EXEC_PROFILE_GRAPH_DEFAULT, EXEC_PROFILE_GRAPH_SYSTEM_DEFAULT

# create the default execution profile pointing at a specific graph
graph_name = 'test'
ep = GraphExecutionProfile(graph_options=GraphOptions(graph_name=graph_name))
cluster = Cluster(execution_profiles={EXEC_PROFILE_GRAPH_DEFAULT: ep})
session = cluster.connect()

# use the system execution profile (or one with no graph_options.graph_name set) when accessing the system API
session.execute_graph("system.graph(name).ifNotExists().create()", {'name': graph_name},

# ... set dev mode or configure graph schema ...

result = session.execute_graph('g.addV("name", "John", "age", 35)')  # uses the default execution profile
vertex = result[0]
type(vertex)  # :class:`.Vertex`

session.execute_graph("system.graph(name).drop()", {'name': graph_name},

By default (with GraphExecutionProfile.row_factory set to graph.graph_object_row_factory()), known graph result types are unpacked and returned as specialized types (Vertex, Edge). If the result is not one of these types, a graph.Result is returned, containing the graph result parsed from JSON and removed from its outer dict. The class has some accessor convenience methods for accessing top-level properties by name (type, properties above), or lists by index:

# dicts with `__getattr__` or `__getitem__`
result = session.execute_graph("[[key_str: 'value', key_int: 3]]", execution_profile=EXEC_PROFILE_GRAPH_SYSTEM_DEFAULT)[0]  # Using system exec just because there is no graph defined
result  # dse.graph.Result({u'key_str': u'value', u'key_int': 3})
result.value  # {u'key_int': 3, u'key_str': u'value'} (dict)
result.key_str  # u'value'
result.key_int  # 3
result['key_str']  # u'value'
result['key_int']  # 3

# lists with `__getitem__`
result = session.execute_graph('[[0, 1, 2]]', execution_profile=EXEC_PROFILE_GRAPH_SYSTEM_DEFAULT)[0]
result  # dse.graph.Result([0, 1, 2])
result.value  # [0, 1, 2] (list)
result[1]  # 1 (list[1])

You can use a different row factory by setting Session.default_graph_row_factory or passing it to Session.execute_graph(). For example, graph.single_object_row_factory() returns the JSON result string`, unparsed. graph.graph_result_row_factory() returns parsed, but unmodified results (such that all metadata is retained, unlike graph.graph_object_row_factory(), which sheds some as attributes and properties are unpacked). These results also provide convenience methods for converting to known types (as_vertex(), as_edge(), as_path()).

Named parameters are passed in a dict to cluster.Session.execute_graph():

result_set = session.execute_graph('[a, b]', {'a': 1, 'b': 2}, execution_profile=EXEC_PROFILE_GRAPH_SYSTEM_DEFAULT)
[r.value for r in result_set]  # [1, 2]

As with all Execution Profile parameters, graph options can be set in the cluster default (as shown in the first example) or specified per execution:

ep = session.execution_profile_clone_update(EXEC_PROFILE_GRAPH_DEFAULT,
session.execute_graph(statement, execution_profile=ep)