MRS Cluster Metadata Overview

MRS's data connections manage external source connections used by components in a cluster. For example, they associate Hive metadata with external relational databases.

• Local metadata: Metadata is stored in the local GaussDB of a cluster. When the cluster is deleted, the metadata is also deleted. To retain the metadata, manually back up the metadata in the database in advance.
• External data connection: You can associate the MRS cluster with an external data connection that is in the same VPC and subnet as the MRS cluster. Metadata is stored in the associated database and is not deleted even if the cluster is deleted. Multiple MRS clusters can share the same metadata.
  MRS clusters support the following types of external data connections:

  • Clusters with Hive installed can connect to RDS for PostgreSQL. The database version is PostgreSQL14.
  • Clusters where Hive or Ranger is installed can connect to RDS for MySQL. The database version is MySQL 5.7.x/MySQL 8.0.
  • Only MRS 3.1.2-LTS.3, MRS 3.1.5, and MRS 3.3.0-LTS clusters can connect to GaussDB(for MySQL).
  • If the cluster supports LakeFormation, you can select LakeFormation as the data connection.

When Hive metadata is switched between different clusters, MRS synchronizes only the permissions in the metadata database of the Hive component. The permission model on MRS is maintained on MRS Manager. Therefore, when Hive metadata is switched between clusters, the permissions of users or user groups cannot be automatically synchronized to MRS Manager of another cluster.