Expanding a Greenplum System

To scale up performance and storage capacity, expand your Greenplum Database system by adding hosts to the system. In general, adding nodes to a Greenplum cluster achieves a linear scaling of performance and storage capacity.

Data warehouses typically grow over time as additional data is gathered and the retention periods increase for existing data. At times, it is necessary to increase database capacity to consolidate different data warehouses into a single database. Additional computing capacity (CPU) may also be needed to accommodate newly added analytics projects. Although it is wise to provide capacity for growth when a system is initially specified, it is not generally possible to invest in resources long before they are required. Therefore, you should expect to execute a database expansion project periodically.

Because of the Greenplum MPP architecture, when you add resources to the system, the capacity and performance are the same as if the system had been originally implemented with the added resources. Unlike data warehouse systems that require substantial downtime in order to dump and restore the data, expanding a Greenplum Database system is a phased process with minimal downtime. Regular and ad hoc workloads can continue while data is redistributed and transactional consistency is maintained. The administrator can schedule the distribution activity to fit into ongoing operations and can pause and resume as needed. Tables can be ranked so that datasets are redistributed in a prioritized sequence, either to ensure that critical workloads benefit from the expanded capacity sooner, or to free disk space needed to redistribute very large tables.

The expansion process uses standard Greenplum Database operations so it is transparent and easy for administrators to troubleshoot. Segment mirroring and any replication mechanisms in place remain active, so fault-tolerance is uncompromised and disaster recovery measures remain effective.

• System Expansion Overview
  You can perform a Greenplum Database expansion to add segment instances and segment hosts with minimal downtime. In general, adding nodes to a Greenplum cluster achieves a linear scaling of performance and storage capacity.
• Planning Greenplum System Expansion
  Careful planning will help to ensure a successful Greenplum expansion project.
• Preparing and Adding Nodes
  Verify your new nodes are ready for integration into the existing Greenplum system.
• Initializing New Segments
  Use the gpexpand utility to initialize the new segments, create the expansion schema, and set a system-wide random distribution policy for the database.
• Redistributing Tables
  Redistribute tables to balance existing data over the newly expanded cluster.
• Removing the Expansion Schema
  To clean up after expanding the Greenplum cluster, remove the expansion schema.

Parent topic: Managing a Greenplum System