Once an hour and at requestor logoff, the usage daemon saves requestor performance details as instances of the Log-Usage class in the pr_perf_stats table. The instances in this class provide a cumulative history of past system usage across all nodes and all requestor types. Analysis of this data can provide valuable insights about the patterns and sources of processing demand, and can be helpful in performance tuning.

Keys of instances in the Log-Usage class

The key of each Log-Usage instance is the pzInsKey column of the pr_perf_stats table. This key is concatenated from the values of the following four properties:

• pxRequestorID – The system-assigned requestor ID for this session
• pxSnapShotTime – Date and time of this snapshot
• pxSnapShotType – Record type
• pxSystemNodeID – Node ID

The first character of the requestor ID identifies a requestor type:

• A – Services ( APP requestor types)
• B – Background requestors ( BATCH requestor type)
• H – Interactive browser users ( BROWSER requestor type)
• P – Portlet users ( PORTLET requestor type)

Identifying a snapshot

The pxSnapshotType column identifies an important value needed to interpret the other values in a record. This column has one of six values:

• INTERVAL – Records cumulative usage statistics for a requestor as of the end of an interval (typically a clock hour).
• PASSIVATED – Records passivation of a requestor, such as occurs when a session times out. The PersistRequestor entry in the prconfig.xml file or dynamic system setting controls passivation.
• TERMINATED – Records log-out, forced time-out, or other termination of a requestor.
• PALCLEAR – Records that a requestor cleared PAL statistics.
• MERGED_AGENTS – Records details from multiple agent requestors.

Identifying an agent or daemon

For agents and daemons, the pyProcLabel property identifies the agent, the index of the row on the Rule-Agent-Queue form, and the activity. The subscript is zero-based. For example, the value Pega-ProCom:2:Assign-Corr.SendCorr in a log identifies processing by the Assign-Corr.SendCorr activity listed the second row of the Agent Queue form for the Pega-RULES agent.

For daemons such as the master agent, the pyProcLabel column is blank.

A usage daemon commits instances of the Log-Usage class to the database table.

The usage daemon saves an instance of the Log-Usage class when a requestor terminates, passivates, activates, and at regular hourly intervals. To minimize the performance effect of new instances, the daemon's write operations are deferred and then committed as a group.

By default, INTERVAL operations record a snapshot at 59 minutes after each hour. For example, if an operator signs on at 11:15 AM and signs off at 11:56 AM, no INTERVAL instances for that requestor are logged.

By default, this daemon wakes every 300 seconds, so the contents of the table might be stale or incomplete by as much as five minutes.

In a multinode cluster, the usage daemons on each node operate independently, so the presence of records in the database table with a recent pxSnapShotTime from one node does not imply that no more records with a similar or earlier pxSnapShotTime value will arrive.

Because agents are requestors, this daemon adds instances to the Log-Usage class for agents even when the system has no interactive users. This behavior is expected.

Some service requestors end a few seconds or less after they start. Typically no INTERVAL instances appear for such requestors. If a service uses pooled requestors, INTERVAL instances may appear for those requestors in the pool once each hour.

To facilitate reporting, all properties of the Log-Usage class are optimized as columns of the pr_perf_stats table. This table does not contain a Storage Stream column.

Except for the properties in the following table, the names and meanings of statistical properties in the Log-Usage class is identical to the names and meanings of those in the Code-Pega-PAL class, which supports the Performance Analyzer tool (PAL).

For technical reasons, Log-Usage properties listed in the following table have a shorter name from the corresponding Code-Pega-PAL properties.

To improve access, the PegaRULES database indexes are defined for the pr_perf_stats table. You can access this table using the pxUserIdentifier, pxSnapshotTime, pxRequestorType, pxSnapShotType, or pxSystemNodeID property values.