Pivotal Greenplum® Command Center 4.0.0 Release Notes

About This Release

Pivotal Greenplum Command Center release 4.0 is a major new release of the Greenplum Database management console.

See Enhancements and Changes in Greenplum Command Center 4.0 for information about new features and changes in this Command Center release.

If your Greenplum Database system has a standby master, you must start Greenplum Command Center on the standby master. When you have finished installing Command Center, see Starting and Stopping the Web Server for steps to start the Command Center web server.

Supported Platforms

Greenplum Command Center 4.0 is compatible with the following platforms.

  • Pivotal Greenplum Database 5.7.0 and higher
  • Red Hat Enterprise Linux 6.x and 7.x
  • CentOS 6.x and 7.x

If you use resource groups and workload management on Red Hat or CentOS 6.x, upgrade your kernel to 2.6.32-696 or higher to benefit from improvements in the Linux cgroups service.

Enhancements and Changes in Greenplum Command Center 4.0

Command Center Installation Changes

Greenplum Command Center 4.0 software, unlike previous releases, is installed on every host in the Greenplum Database cluster. The Command Center web server and backend run on the standby master, if your Greenplum Database cluster has a standby master. If there is no standby master, Command Center runs on the master host instead.

To modify the Command Center installation—for example to enable or disable SSL or install Command Center on new or replaced hosts—just re-execute the installer and restart Command Center. It is not necessary to uninstall Command Center before reinstalling.

There is one Command Center installation per Greenplum Database cluster. It is no longer necessary to create Command Center instances after installing the software.

The gpcmdr command-line utility is replaced with the new gpcc utility. Use the gpcc utility to start and stop Command Center and metrics collection agents, check Command Center status, and enable or disable Kerberos authentication.

In previous releases, the gpmon role required only local connections to databases on the Greenplum master host. In Greenplum Command Center 4.0, the gpmon user must be able to connect to databases from the host running the Command Center web server and backend, which requires adding a host entry to the pg_hba.conf authentication configuration file.

Real-time Query Metrics

Greenplum Command Center 4.0 introduces real-time query metrics for Pivotal Greenplum Database 5.7 and above. This new feature combines the following new features in Greenplum Database and Greenplum Command Center:

  • Greenplum Database saves query execution metrics in shared memory while queries execute.
  • A new Greenplum Database metrics collection extension, included with Pivotal Greenplum Database, emits the saved metrics as UDP datagrams.
  • A new Greenplum Command Center metrics collection agent running on each Greenplum Database host receives the datagrams and posts metrics to the Greenplum Command Center backend. The Command Center backend starts and manages the metrics collection agents.

The Command Center Query monitor view updates in real time so you can see queries that are waiting to execute and the current status and resource usage for queries that are running.

Metrics collection now includes lock and spill file information. On the Query Monitor, you can see which queries are blocked and which queries hold the locks blocking them. The Query Monitor shows the total size of spill files created on all segments for each query.

Installing the gpperfmon database remains a prerequisite for Command Center. The gpperfmon database is the source for query history displayed in the Command Center user interface. The new real-time metrics are not persisted and are not directly related to the metrics collected and persisted in the gpperfmon database.

Workload Management

Workload management is now an integrated Command Center feature rather than a separate product. Workload management is available in Command Center only after resource groups have been enabled in Greenplum Database by changing the gp_resource_manager server configuration parameter from 'queue' to 'group' and enabling Linux control groups (cgroups).

In Command Center 4.0, workload management allows you to assign transactions to Greenplum Database resource groups at execution time by evaluating the current database role and query tags against workload assignment filters you define in Command Center. Query tags are user-defined name=value parameters that you define in the gpcc.query_tags database session parameter. You can define multiple query tags separated by semicolons. Set query tags in a Greenplum Database session either as a parameter in the database connection URL or by executing SET gpcc.query_tags TO '<tag1>=<val1>;<tag2>=<val2>;...' in the database session.

When a transaction is about to execute, the current database role and query tags are compared to the workload assignment filters that you have created in Command Center. If a match is found, the transaction is assigned to a resource group according to the workload management filter. Otherwise, the transaction is assigned to the database user’s resource group, which is the default behavior when Command Center workload management is not enabled.

Workload management uses the gp_wlm database extension included with Pivotal Greenplum Database.

Unimplemented Features

Some features available in previous Greenplum Command Center releases are not yet implemented in Command Center 4.0.

  • The Basic, Operator Basic, and Operator permission levels are not yet implemented. You can only change a role’s permission level between Self Only and Admin.
  • The ability for a Command Center admin to post a message to the Query Monitor view is not yet implemented.
  • The multi-cluster view has been removed.