How Hive Configurations are Propagated to Hive Clients

Because the Hive service does not have worker roles, another mechanism is needed to enable the propagation of client configurations to the other hosts in your cluster. In Cloudera Manager gateway roles fulfill this function. Whether you add a Hive service at installation time or at a later time, ensure that you assign the gateway roles to hosts in the cluster. If you do not have gateway roles, client configurations are not deployed.

Considerations When Upgrading Cloudera Manager

Cloudera Manager 4.5 added support for Hive, which includes the Hive Metastore Server role type. This role manages the metastore process when Hive is configured with a remote metastore.

When upgrading from Cloudera Manager versions lower than 4.5, Cloudera Manager automatically creates new Hive services to capture the previous implicit Hive dependency from Hue and Impala. Your previous services continue to function without impact. If Hue was using a Hive metastore backed by a Derby database, the newly created Hive Metastore Server also uses Derby. Because Derby does not allow concurrent connections, Hue continues to work, but the new Hive Metastore Server does not run. The failure is harmless (because nothing uses this new Hive Metastore Server at this point) and intentional, to preserve cluster functionality as it existed before upgrade. Cloudera recommends switching to a different supported database because of the limitations of a Derby-backed Hive metastore.

Cloudera Manager provides a Hive configuration option to bypass the Hive Metastore Server. When this configuration is enabled, Hive clients, Hue, and Impala connect directly to the Hive metastore database. In releases lower than Cloudera Manager 4.5, Hue and Impala connected directly to the Hive metastore database, so the bypass mode is enabled by default when upgrading to Cloudera Manager 4.5 and higher. This ensures that the upgrade does not disrupt your existing setup. You should plan to disable the bypass mode, especially when using CDH 4.2 and higher. Using the Hive Metastore Server is the recommended configuration, and the WebHCat Server role requires the Hive Metastore Server to not be bypassed. To disable bypass mode, see Disabling Bypass Mode .

Cloudera Manager 4.5 and higher also supports HiveServer2 with CDH 4.2. In CDH 4, HiveServer2 is not added by default, but can be added as a new role under the Hive service (see Role Instances). In CDH 5, HiveServer2 is a mandatory role.

Disabling Bypass Mode

Minimum Required Role: Configurator (also provided by Cluster Administrator, Full Administrator)

In bypass mode Hive clients directly access the metastore database instead of using the Hive Metastore Server for metastore information.

1. Go to the Hive service.
2. Click the Configuration tab.
3. Select Scope > HIVE service_name (Service-Wide)
4. Select Category > Advanced.
5. Clear the Bypass Hive Metastore Server property.
6. Click Save Changes to commit the changes.
7. Re-deploy Hive client configurations.
8. Restart Hive and any Hue or Impala services configured to use that Hive service.