4. Resolving General Problems

 4.1. Problem: Hive developers may encounter an exception error message during Hive Service Check

MySQL is the default database used by the Hive metastore. Depending on several factors, such as the version and configuration of MySQL, a Hive developer may see an exception message similar to the following one:

An exception was thrown while adding/validating classes) : Specified key was too long; max key length is 767 bytes 

 4.1.1. Solution

Administrators can resolve this issue by altering the Hive metastore database to use the Latin1 character set, as shown in the following example:

mysql> ALTER DATABASE {metastore_database_name} character set latin1;

 4.2. Problem: API calls for PUT, POST, DELETE respond with a "400 - Bad Request"

Removing a registered host not added to a cluster. curl command and REST API calls require a header element.

 4.2.1. Solution

Starting with Ambari 1.4.2, you must include the "X-Requested-By" header with the REST API calls.

For example, if using curl, include the -H "X-Requested-By: ambari" option.

curl -u admin:admin -H "X-Requested-By: ambari" -X DELETE http://{ambari-host}:8080/api/v1/hosts/host1

 4.3. Problem: Nagios alerts for CPU utilization show as UNKNOWN

Alerts for Master components such as "NameNode CPU Utilization" and "ResourceManager CPU Utilization" show as "UNKNOWN".

 4.3.1. Solution

Nagios uses Simple Network Management Protocol (SNMP) to check CPU utilization. Be sure SNMP is started and port 161 is accessible between the Nagios Server and the hosts running the Master components.

service snmpd start

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