Use MySQL for the Hive Metastore
The metadata for Hive tables and partitions are stored in the Hive Metastore. By default, the Hive Metastore stores all Hive metadata in an embedded Apache Derby database in MapR-FS. Derby only allows one connection at a time; if you want multiple concurrent Hive sessions, you can use MySQL for the Hive Metastore.
Prerequisites
- Make sure MySQL is installed on the machine on which you want to run the Metastore,
and make sure you are able to connect to the MySQL Server from the Hive machine. You
can run the Hive Metastore on any machine that is accessible from Hive. You can test
this with the following
command:
mysql -h <hostname> -u <user>
- The database administrator must create a database for the Hive metastore data, and
the username specified in
javax.jdo.option.ConnectionUserName
must have permissions to access it. The database can be specified using theConnectionURL
parameter. The tables and schemas are created automatically when the metastore is first started.
About this task
Procedure
-
Update the
hive-site.xml
in the Hive configuration directory (/opt/mapr/hive/hive-<version>/conf
) with the following contents:<configuration> <property> <name>javax.jdo.option.ConnectionURL</name> <value>jdbc:mysql://localhost:3306/hive?createDatabaseIfNotExist=true</value> <description>JDBC connect string for a JDBC metastore</description> </property> <property> <name>javax.jdo.option.ConnectionDriverName</name> <value>com.mysql.jdbc.Driver</value> <description>Driver class name for a JDBC metastore</description> </property> <property> <name>javax.jdo.option.ConnectionUserName</name> <value>root</value> <description>username to use against metastore database</description> </property> <property> <name>javax.jdo.option.ConnectionPassword</name> <value><fill in with password></value> <description>password to use against metastore database</description> </property> <property> <name>hive.metastore.uris</name> <value>thrift://localhost:9083</value> </property> </configuration
-
To connect to an existing MySQL metastore, make sure
the
ConnectionURL
parameter and theThrift URIs
parameters inhive-site.xml
point to the metastore's host and port. -
To set a specific port for Thrift URIs, add the
command
export METASTORE_PORT=<port>
into the filehive-env.sh
(ifhive-env.sh
does not exist, create it in the Hive configuration directory). Example:export METASTORE_PORT=9083
-
Start the Hive Metastore service using one of the following commands:
If you want the Hive Metastore to be managed by Warden, the maprcli, and the MCS:
maprcli node services -name hivemeta -action start -nodes <space delimited list of nodes>
If you want the Hive Metastore to be managed with standard hive commands:/opt/mapr/hive/hive-<version>/bin/hive --service metastore
You can use also use
nohup hive --service metastore
to run metastore in the background.WARNING: If you have not configured a MySQL Metastore, do not run the Hive shell from a MapR NFS mount location. If you try to do this, Hive will fail. The same problem will occur if you use thehive-site.xml
file to configure the Metastore on a MapR NFS mount location. Avoid both of these configurations.