For a partitioned table, collects statistics for the root partition when the ANALYZE command is run on the table. The Pivotal Query Optimizer uses the root partition statistics when generating a query plan. The legacy query optimizer does not use these statistics. If you set the value of the server configuration parameter optimizer to on, set the value of this parameter to on and run the command ANALYZE or ANALYZE ROOTPARTITION on partitioned tables to ensure the proper statistics have been collected.

For information about the legacy query optimizer and the Pivotal Query Optimizer, see "Querying Data" in the Greenplum Database Administrator Guide.