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Install a compatible version of MySQL server and database.

Configure and start MySQL server.

1. If the MySQL server is running, stop it and delete the old InnoDB log files.

   If you need to save your old InnoDB log files copy them to a directory of your choosing, backup-path before deletion.

   sudo service mysqld stop
   cp /var/lib/mysql/ib_logfile* backup-path
   rm -rf /var/lib/mysql/ib_logfile*

2. In the MySQL configuration file (typically /etc/my.cnf), append the following properties at the end of the [mysqld] section. Set datadir to the directory your choice. This directory must have a minimum capacity of 500GB.

   key_buffer_size = 256M
   max_allowed_packet = 32M
   sort_buffer_size = 32M
   # Do not add query_cache_size when using MySQL 8 as it is no longer valid
   query_cache_size = 64M
   max_connections = 500
   max_connect_errors = 2000000000
   open_files_limit = 10000
   port-open-timeout = 121
   expire-logs-days = 1
   character_set_server = utf8
   collation_server = utf8_unicode_ci
   innodb_open_files = 2000
   innodb_file_per_table = 1
   innodb_data_file_path = ibdata1:100M:autoextend
   # The innodb_buffer_pool_size depends on load and cluster size.
   # On a dedicated machine, it can be 50% of the RAM size.
   # Using 1G is the absolute minimum. For a large cluster, we use 48G.
   innodb_buffer_pool_size = 4G
   innodb_flush_method = O_DIRECT
   innodb_log_file_size = 256M
   innodb_log_buffer_size = 64M
   innodb_flush_log_at_trx_commit = 2
   innodb_lock_wait_timeout = 50
   innodb_thread_concurrency = 20
   innodb_read_io_threads = 16
   innodb_write_io_threads = 4
   binlog_format = mixed
   # if SSD disk is used uncomment the line below
   #innodb_io_capacity = 4000

3. Ensure MySQL server starts at boot time and then start the MySQL server

   • On CentOS 6:

     sudo chkconfig mysqld on
     sudo service mysqld start

   • On CentOS 7:

     sudo systemctl enable mysqld
     sudo systemctl start mysqld

4. Check the used and free space on the volume specified by MySQL's datadir property in the MySQL configuration file (typically /etc/my.cnf):

   • Used and Free Space

     sudo grep "^datadir=" /etc/my.cnf | awk -F"[=]" '{print $2}' | sudo xargs du -sh
     sudo grep "^datadir=" /etc/my.cnf | awk -F"[=]" '{print $2}' | sudo xargs df -h 

Install the MySQL JDBC driver.

1. Download the JDBC driver for MySQL to /tmp. Then navigate to /tmp and extract the driver.

   wget https://dev.mysql.com/get/Downloads/Connector-J/mysql-connector-java-5.1.47.tar.gz -O /tmp/mysql-connector-java-5.1.47.tar.gz
   cd /tmp
   tar xvzf /tmp/mysql-connector-java-5.1.47.tar.gz

Install MySQL.

yum install mysql

Copy the MySQL JDBC JAR to /usr/local/unravel/share/java/.

sudo mkdir -p /usr/local/unravel/share/java
sudo cp /tmp/mysql-connector-java-5.1.47/mysql-connector-java-5.1.47.jar /usr/local/unravel/share/java
sudo cp /tmp/mysql-connector-java-5.1.47/mysql-connector-java-5.1.47.jar /usr/local/unravel/dlib/unravel

Configure Unravel to connect to the MySQL server.

1. Using mysql, create a database and user for Unravel.

   mysql
   mysql> CREATE DATABASE unravel_mysql_prod;
   mysql> CREATE USER 'unravel'@'localhost' IDENTIFIED BY 'password';
   mysql> GRANT ALL PRIVILEGES ON unravel_mysql_prod.* TO 'unravel'@'localhost';

2. In /usr/local/unravel/etc/unravel.properties, update the following properties:

   Important

   These properties define the connection to Unravel's database, not the Hive's database.

   If you are using

   • Unravel's bundled database (PostgreSQL), don't modify these properties.

   • An external database, for example MySQL, update these properties as instruction in Install MySQL.

   Property/Description	Set by user	Unit	Default
   unravel.jdbc.username Unravel database user.	Required	string	-
   unravel.jdbc.password Password for unravel.jdbc.username.	Required	string	-
   unravel.jdbc.url URL for jdbc, determined by your database. Example: jdbc:mysql://127.0.0.1:3306/unravel_mysql_prod	Required	string (path)	-

   For example,

   unravel.jdbc.username=unravel
   unravel.jdbc.password=password
   unravel.jdbc.url=jdbc:mysql://127.0.0.1:3306/unravel_mysql_prod

   Important

   If you installed MySQL 8.0, add:

   unravel.jdbc.url.params=disableMariaDbDriver

3. Create a schema for Unravel tables.

   sudo /usr/local/unravel/dbin/db_schema_upgrade.sh

4. Create the default admin user for Unravel UI.

   sudo /usr/local/unravel/install_bin/db_initial_inserts.sh | /usr/local/unravel/install_bin/db_access.sh

Disable PostgreSQL.

Once you have successfully configured Unravel to use the MySQL database, disable the unravel_pg PostgreSQL database and deactivate the service for all run levels. In other words, run this command on the Unravel host(s):

sudo service unravel_pg stop; sudo chkconfig unravel_pg off