Workload Manager Metric Reference

This topic lists the metrics Greenplum Workload Manager collects. These metrics can be used in the when clause of a Workload Manager rule to select Greenplum Database queries that trigger an action. Metrics in when clauses are prefixed with their scope, for example:

host:cpu_util > 35

The metric, in this example, is cpu_util and the scope is host. This metric will match any host with greater than 35% CPU utilization. The following expression matches a single postgres process on any host using more than 35% CPU:

host:pid:cpu_util > 35 and host:pid:name = 'postgres'

Metrics may also be listed in the optional including clause of a rule so that their values are saved with the record or event data when a rule is matched. When adding metrics to the including clause, omit the scope; Workload Manager finds the metric in the scope matched by the when clause.

The metrics are arranged in the following categories:

• Connections – number of backend connections and connections to the master
• Identification – names of users, hosts, databases, ports, processes, and so on
• Transactions – information about the current transaction, queries within transactions, and numbers of transactions committed and rolled back in the database
• Date/Time – date and time metrics for a host
• CPU – CPU utilization for hosts, processes, and sessions
• Memory – memory utilization for processes and queries
• Vmem - vmem utilization for segments and sessions
• Spill – number of spill files (work files) created and total spill file size for a query
• I/O – disk read/write statistics for databases, processes, and queries
• Skew – disk read/write skew and memory skew for queries

Connections

Identification

Transactions

Date/Time

Note: Date and time values are stored in UTC standard time and converted to the local time zone for display. Use the SHOW TIME ZONE and SET TIME ZONE commands in psql to view and set the local time zone.

CPU

Memory

Vmem

To use the vmem metrics in Workload Manager, you must first run the gp_session_state.sql script included with Greenplum Database on the postgres database. This is a one-time task.

The script creates the view session_level_memory_consumption in the database. See Viewing Session Memory Usage Information in the Greenplum Database Administrator Guide for information about this view and the gp_session_state.sql script.

Execute the script with the following command:

psql -d postgres -f $GPHOME/share/postgresql/contrib/gp_session_state.sql

Following are recommended configuration adjustments when using vmem metrics. Enter the commands at the gp-wlm command-line:

config modify gpdb_stats publish_frequency = 0.75
config modify gpdb_stats collect_frequency = 0.5
config modify rulesengine engine:rule_frequency = 0.5

Spill

I/O

Skew