Command Center Database Reference

posted Nov 8, 2012, 1:01 PM by Sachi Ojha
The Command Center database consists of three sets of tables; now tables store data on current system metrics such as active queries, history tables store data on historical metrics, and tail tables are for data in transition. Tail tables are for internal use only and should not be queried by users. The now and tail data are stored as text files on the master host file system, and accessed by the Command Center database via external tables. The history tables are regular database tables stored within the Command Center (gpperfmon) database.

The database consists of three sets of tables:
•now tables store data on current system metrics such as active queries.
•history tables store data historical metrics.
•tail tables are for data in transition. These tables are for internal use onlz and should not be queried by endusers.

The now and tail data are stored as text files on the master file system, and accessed by Command Center database (gpperfmon) via external tables. The history tables are regular database tables stored within the Command Center database.

There are the following categories of tables:

1. The database_* tables store query workload information for a Greenplum Database instance.

2. The emcconnect_history table displays information about ConnectEMC events and alerts. ConnectEMC events are triggered based on a hardware failure, a fix to a failed hardware component, or a Greenplum Database startup. Once an ConnectEMC event is triggered, an alert is sent to EMC Support.

3. The filerep_* tables store health and status metrics for the file replication process. This process is how high-availability/mirroring is achieved in Greenplum Database instance. Statistics are maintained for each primary-mirror pair.

4. The health_* tables store system health metrics for the EMC Data Computing Appliance.

5. The interface_stats_* tables store statistical metrics for each active interface of a Greenplum Database instance. Note: These tables are in place for future use and are not currently populated.

6. The iterators_* tables store information about query plan iterators and their metrics. A query iterator refers to a node or operation in a query plan.

7. The queries_* tables store high-level query status information.

8. The segment_* tables store memory allocation statistics for the Greenplum Database segment instances.

9. The socket_stats_* tables store statistical metrics about socket usage for a Greenplum Database instance. Note: These tables are in place for future use and are not currently populated.

10. The system_* tables store system utilization metrics.

11. The tcp_stats_* tables store statistical metrics about TCP communications for a Greenplum Database instance. Note: These tables are in place for future use and are not currently populated.

12. The udp_stats_* tables store statistical metrics about UDP comm unications for a Greenplum Database instance. Note: These tables are in place for future use and are not currently populated.

The Command Center database also contains the following views:

1. The dynamic_memory_info view shows an aggregate of all the segments per host and the amount of dynamic memory used per host.

2. The iterators_*_rollup set of views summarize the query iterator metrics across all segments in the system.

3. The memory_info view shows per-host memory information from the system_history and segment_history tables.
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