Creating a graph

Creating a graph.

Depending on the DSE Graph schema mode, DataStax Studio will have differing behavior. In Production mode, DataStax Studio will not auto-create a graph, and the graph must be created in the Gremlin console. In Development mode, DataStax Studio creates a graph and aliases the graph to a graph traversal automatically for each connection that is created.

DataStax Studio creates a graph automatically for each connection that is created. In Gremlin console, a graph must be manually created. In addition to creating the graph, a graph traversal must be aliased to the graph in order to run queries.

Procedure

Studio

Start DSE Graph.
Install and start Studio. Also create a Studio notebook, if needed.
In DataStax Studio, create a connection. Choose a graph name; any graph previously unused will work.
In DataStax Studio, create a notebook. Select the connection created in the last step.

A blank notebook will open with a single cell. DSE Graph runs a Gremlin Server tinkerpop.server on each DSE node. DataStax Studio automatically connects to the Gremlin Server, and if it doesn't exist, creates a graph using the connection information. The graph is stored as one graph instance per DSE database keyspace with a replication factor of 1 and a strategy of SimpleStrategy. Once a graph exists, a graph traversal g is configured that will allow graph traversals to be executed. Graph traversals are used to query the graph data and return results. A graph traversal is bound to a specific traversal source which is the standard OLTP traversal engine.

Gremlin console

Start the Gremlin console.
Create a simple graph with default settings to hold the data.
```
gremlin> system.graph('food').create()
```
```
==>null
```

Create a graph with non-default replication, systemReplication, and configuration settings:

system.graph('food2').
  replication("{'class' : 'NetworkTopologyStrategy', 'dc1' : 3 }").
  systemReplication("{'class' : 'NetworkTopologyStrategy', 'dc1' : 3 }").
  option("graph.schema_mode").set("Production").
  option("graph.allow_scan").set("false").
  option("graph.default_property_key_cardinality").set("multiple").
  option("graph.tx_groups.*.write_consistency").set("QUORUM").create()

CAUTION: For graphs created in multi-datacenter clusters, the DSE database settings must use NetworkTopologyStrategy and a replication factor greater than one. If the graph is created with a replication setting of SimpleStrategy and a replication factor of 1, the graph data will be stored across the multiple datacenters rather than localizing the data in the graph datacenter.

The default replication strategy for a multi-datacenter graph is NetworkTopologyStrategy, whereas for a single datacenter, the replication strategy will default to SimpleStrategy. The number of nodes will determine the default replication factors:


number of nodes per datacenter	graph_name replication factor	graph_name_system replication factor
1-3	number of nodes per datacenter	number of nodes per datacenter
4	3	4
5 or greater	3	5

On the remote Gremlin Server, set the alias for the graph traversal g to the graph traversal specified in food. To run traversals, the graph traversal must be aliased to a graph.
```
gremlin> :remote config alias g food.g
```
```
==>g=food.g
```