The udp_stats_* tables store statistical metrics about UDP communications for a Greenplum Database instance.

These tables are in place for future use and are not currently populated.

There are three system tables, all having the same columns:

• udp_stats_now is an external table whose data files are stored in $MASTER_DATA_DIRECTORY/gpperfmon/data.
• udp_stats_tail is an external table whose data files are stored in $MASTER_DATA_DIRECTORY/gpperfmon/data. This is a transitional table for UDP statistical data that has been cleared from udp_stats_now but has not yet been committed to udp_stats_history. It typically only contains a few minutes worth of data.
• udp_stats_history is a regular table that stores historical UDP statistical metrics. It is pre-partitioned into monthly partitions. Partitions are automatically added in two month increments as needed. Administrators must drop old partitions for the months that are no longer needed.