在Cosmos DB中优化gremlin查询

Question

I run the queries likes the following in gremlin in Cosmos Graph:

g.V().hasLabel('vertex_label').limit(1)

This query is problematic in concern of size of data which returned from DB as this query returns all inE and outE of the selected vertex. The question is how can I optimize this query in notion of size of query result?

Answer 1

As mentioned, the mentioned query returns a vertex with all its dependencies and connections. Therefore, it can be problematic in high volume of data (when there are a lot of connection with the specified vertex). Hence, We can optimize our queries using something likes properties , properyMap , values ,and valueMap . In sum, valueMap(true) in the end of related queries can be useful and minimize the size of the transferred data from Cosmos. For example:

g.V().hasLabel('play').limit(1).valueMap(true)

The boolean value is for getting id and label of the vertex in addition to vertex properties.

Also, If there is any notion of optimization in the structure of a query, you can find more in this link .

Answer 2

How are you using CosmosDB Graph, via Microsoft.Azure.Graphs SDK or Gremlin server?

If you are using Microsoft.Azure.Graphs, the latest version ( 0.2.4-preview as of posting) supports specifying the GraphSONFormat as a parameter on DocumentClient.CreateGremlinRequest(..) . You can choose from either GraphSONFormat.Normal or GraphSONFormat.Compact and Compact should be the default if it is not supplied.

For the CosmosDB Gremlin server, Compact is also the default behavior.

With GraphSONFormat.Compact , vertex results won't include edges and as a result, outE and inE fetches can be skipped when fetching the vertex. GraphSONFormat.Normal will return the full GraphSON response if this is desired.

Additional Note : There are optimizations on limit() that will be included in the next release of SDK/server, so I would expect additional perf gains on the traversal example that you provided when the release becomes available.