Initializing a Greenplum Database System

Initializing a Greenplum Database System

This chapter describes how to initialize a Greenplum Database database system. The instructions in this chapter assume you have already installed the Greenplum Database software on all of the hosts in the system according to the instructions in Configuring Your Systems and Installing Greenplum.

This chapter contains the following topics:

Overview

Because Greenplum Database is distributed, the process for initializing a Greenplum Database management system (DBMS) involves initializing several individual PostgreSQL database instances (called segment instances in Greenplum).

Each database instance (the master and all segments) must be initialized across all of the hosts in the system in such a way that they can all work together as a unified DBMS. Greenplum provides its own version of initdb called gpinitsystem, which takes care of initializing the database on the master and on each segment instance, and starting each instance in the correct order.

After the Greenplum Database database system has been initialized and started, you can then create and manage databases as you would in a regular PostgreSQL DBMS by connecting to the Greenplum master.

Initializing Greenplum Database

These are the high-level tasks for initializing Greenplum Database:

  1. Make sure you have completed all of the installation tasks described in Configuring Your Systems and Installing Greenplum.
  2. Create a host file that contains the host addresses of your segments. See Creating the Initialization Host File.
  3. Create your Greenplum Database system configuration file. See Creating the Greenplum Database Configuration File.
  4. By default, Greenplum Database will be initialized using the locale of the master host system. Make sure this is the correct locale you want to use, as some locale options cannot be changed after initialization. See Configuring Localization Settings for more information.
  5. Run the Greenplum Database initialization utility on the master host. See Running the Initialization Utility.

Creating the Initialization Host File

The gpinitsystem utility requires a host file that contains the list of addresses for each segment host. The initialization utility determines the number of segment instances per host by the number host addresses listed per host times the number of data directory locations specified in the gpinitsystem_config file.

This file should only contain segment host addresses (not the master or standby master). For segment machines with more than one network interface, this file should list the host address names for each interface — one per line.

Note: The Greenplum Database segment host naming convention is sdwN where sdw is a prefix and N is an integer. For example, on a Greenplum Database DCA system, segment host names would be sdw1, sdw2 and so on. For hosts with multiple interfaces, the convention is to append a dash (-) and number to the host name. For example, sdw1-1 and sdw1-2 are the two interface names for host sdw1.

To create the initialization host file

  1. Log in as gpadmin.
    $ su - gpadmin
  2. Create a file named hostfile_gpinitsystem. In this file add the host address name(s) of your segment host interfaces, one name per line, no extra lines or spaces. For example, if you have four segment hosts with two network interfaces each:
    sdw1-1
    sdw1-2
    sdw2-1
    sdw2-2
    sdw3-1
    sdw3-2
    sdw4-1
    sdw4-2
  3. Save and close the file.
Note: If you are not sure of the host names and/or interface address names used by your machines, look in the /etc/hosts file.

Creating the Greenplum Database Configuration File

Your Greenplum Database configuration file tells the gpinitsystem utility how you want to configure your Greenplum Database system. An example configuration file can be found in $GPHOME/docs/cli_help/gpconfigs/gpinitsystem_config.

To create a gpinitsystem_config file

  1. Log in as gpadmin.
    $ su - gpadmin
  2. Make a copy of the gpinitsystem_config file to use as a starting point. For example:
    $ cp $GPHOME/docs/cli_help/gpconfigs/gpinitsystem_config \
         /home/gpadmin/gpconfigs/gpinitsystem_config
  3. Open the file you just copied in a text editor.

    Set all of the required parameters according to your environment. See gpinitsystem for more information. A Greenplum Database system must contain a master instance and at least two segment instances (even if setting up a single node system).

    The DATA_DIRECTORY parameter is what determines how many segments per host will be created. If your segment hosts have multiple network interfaces, and you used their interface address names in your host file, the number of segments will be evenly spread over the number of available interfaces.

    Here is an example of the required parameters in the gpinitsystem_config file:

    ARRAY_NAME="EMC Greenplum DW"
    SEG_PREFIX=gpseg
    PORT_BASE=40000 
    declare -a DATA_DIRECTORY=(/data1/primary /data1/primary 
    /data1/primary /data2/primary /data2/primary /data2/primary)
    MASTER_HOSTNAME=mdw 
    MASTER_DIRECTORY=/data/master 
    MASTER_PORT=5432 
    TRUSTED SHELL=ssh
    CHECK_POINT_SEGMENTS=8
    ENCODING=UNICODE
  4. (Optional) If you want to deploy mirror segments, uncomment and set the mirroring parameters according to your environment. Here is an example of the optional mirror parameters in the gpinitsystem_config file:
    MIRROR_PORT_BASE=50000
    REPLICATION_PORT_BASE=41000
    MIRROR_REPLICATION_PORT_BASE=51000
    declare -a MIRROR_DATA_DIRECTORY=(/data1/mirror /data1/mirror /data1/mirror /data2/mirror /data2/mirror /data2/mirror)
    Note: You can initialize your Greenplum system with primary segments only and deploy mirrors later using the gpaddmirrors utility.
  5. Save and close the file.

Running the Initialization Utility

The gpinitsystem utility will create a Greenplum Database system using the values defined in the configuration file.

To run the initialization utility

  1. Run the following command referencing the path and file name of your initialization configuration file (gpinitsystem_config) and host file (hostfile_gpinitsystem). For example:
    $ cd ~
    $ gpinitsystem -c gpconfigs/gpinitsystem_config -h gpconfigs/hostfile_gpinitsystem

    For a fully redundant system (with a standby master and a spread mirror configuration) include the -s and -S options. For example:

    $ gpinitsystem -c gpconfigs/gpinitsystem_config -h gpconfigs/hostfile_gpinitsystem \
      -s standby_master_hostname -S
  2. The utility will verify your setup information and make sure it can connect to each host and access the data directories specified in your configuration. If all of the pre-checks are successful, the utility will prompt you to confirm your configuration. For example:
    => Continue with Greenplum creation? Yy/Nn
  3. Press y to start the initialization.
  4. The utility will then begin setup and initialization of the master instance and each segment instance in the system. Each segment instance is set up in parallel. Depending on the number of segments, this process can take a while.
  5. At the end of a successful setup, the utility will start your Greenplum Database system. You should see:
    => Greenplum Database instance successfully created.

Troubleshooting Initialization Problems

If the utility encounters any errors while setting up an instance, the entire process will fail, and could possibly leave you with a partially created system. Refer to the error messages and logs to determine the cause of the failure and where in the process the failure occurred. Log files are created in ~/gpAdminLogs.

Depending on when the error occurred in the process, you may need to clean up and then try the gpinitsystem utility again. For example, if some segment instances were created and some failed, you may need to stop postgres processes and remove any utility-created data directories from your data storage area(s). A backout script is created to help with this cleanup if necessary.

Using the Backout Script

If the gpinitsystem utility fails, it will create the following backout script if it has left your system in a partially installed state:

~/gpAdminLogs/backout_gpinitsystem_<user>_<timestamp>

You can use this script to clean up a partially created Greenplum Database system. This backout script will remove any utility-created data directories, postgres processes, and log files. After correcting the error that caused gpinitsystem to fail and running the backout script, you should be ready to retry initializing your Greenplum Database array.

The following example shows how to run the backout script:

$ sh backout_gpinitsystem_gpadmin_20071031_121053

Setting Greenplum Environment Variables

You must configure your environment on the Greenplum Database master (and standby master). A greenplum_path.sh file is provided in your $GPHOME directory with environment variable settings for Greenplum Database. You can source this file in the gpadmin user's startup shell profile (such as .bashrc).

The Greenplum Database management utilities also require that the MASTER_DATA_DIRECTORY environment variable be set. This should point to the directory created by the gpinitsystem utility in the master data directory location.

Note: The greenplum_path.sh script changes the operating environment in order to support running the Greenplum Database-specific utilities. These same changes to the environment can negatively affect the operation of other system-level utilities, such as ps or yum. Use separate accounts for performing system administration and database administration, instead of attempting to perform both functions as gpadmin.

To set up your user environment for Greenplum

  1. Make sure you are logged in as gpadmin:
    $ su - gpadmin
  2. Open your profile file (such as .bashrc) in a text editor. For example:
    $ vi ~/.bashrc
  3. Add lines to this file to source the greenplum_path.sh file and set the MASTER_DATA_DIRECTORY environment variable. For example:
    source /usr/local/greenplum-db/greenplum_path.sh
    export MASTER_DATA_DIRECTORY=/data/master/gpseg-1
  4. (Optional) You may also want to set some client session environment variables such as PGPORT, PGUSER and PGDATABASE for convenience. For example:
    export PGPORT=5432
    export PGUSER=gpadmin export PGDATABASE=default_login_database_name
  5. (Optional) If you use RHEL 7 or CentOS 7, add the following line to the end of the .bashrc file to enable using the ps command in the greenplum_path.sh environment:
    export LD_PRELOAD=/lib64/libz.so.1 ps
  6. Save and close the file.
  7. After editing the profile file, source it to make the changes active. For example:
    $ source ~/.bashrc
    
  8. If you have a standby master host, copy your environment file to the standby master as well. For example:
    $ cd ~
    $ scp .bashrc standby_hostname:`pwd`
Note: The .bashrc file should not produce any output. If you wish to have a message display to users upon logging in, use the .profile file instead.

Next Steps

After your system is up and running, the next steps are:

Allowing Client Connections

After a Greenplum Database is first initialized it will only allow local connections to the database from the gpadmin role (or whatever system user ran gpinitsystem). If you would like other users or client machines to be able to connect to Greenplum Database, you must give them access. See the Greenplum Database Administrator Guide for more information.

Creating Databases and Loading Data

After verifying your installation, you may want to begin creating databases and loading data. See Defining Database Objects and Loading and Unloading Data in the Greenplum Database Administrator Guide for more information about creating databases, schemas, tables, and other database objects in Greenplum Database and loading your data.