如何从E类集群读取边？集群查询返回空值求助

Hey there! Let's figure out why your query select from cluster:[e_1, e_2] is returning null, especially since the same pattern works for IP-class clusters. Here are actionable steps to diagnose and fix the issue:

• Verify cluster identifiers are correct
  Double-check that e_1 and e_2 are the exact, valid identifiers for your edge clusters. Unlike IP-class clusters, edge clusters might follow a specific naming convention—for example, requiring a prefix like edge_ or using a system-generated unique ID instead of your custom alias. Try running show clusters (adjust the command to match your database's syntax) to list all available clusters and confirm the exact names of your target edge clusters.

• Check edge cluster status and data presence
  First, test querying a single edge cluster with select from cluster:e_1 to see if it returns data. If this also returns null:

  • Confirm the cluster is online and healthy using a status check command (e.g., show cluster status e_1). Offline or failed clusters will return empty results.
  • Verify that the edge cluster actually contains edge data. It's possible the cluster was provisioned but never populated with edges, or data was accidentally deleted.

• Ensure your query syntax targets edges explicitly
  Some graph databases default to querying vertices when using select from cluster:[...], even if it worked for IP-class clusters (maybe those clusters are configured to prioritize edge data). Try modifying your query to explicitly target edges, like:

  select edges from cluster:[e_1, e_2]
  

  Or specify the edge label if you're looking for a specific type:

  select edges where label = 'your_edge_label' from cluster:[e_1, e_2]
  

• Validate permissions for edge clusters
  Edge clusters often have stricter permission controls than IP-class clusters. Confirm that your user account has the READ permission for both e_1 and e_2 clusters. You can check this with a permission query (e.g., show user permissions your_username) and adjust permissions if needed via your database's access control settings.

• Check for cluster configuration mismatches
  IP-class clusters might be configured with a default data type (edges) that edge clusters don't inherit. Review your cluster configuration settings to see if edge clusters require an explicit data type parameter in the query, or if there's a setting that restricts edge visibility by default.

内容的提问来源于stack exchange，提问作者Ronald Feri