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How to analyze system-wide usage with the Log-Usage class

Instances of the Log-Usage class support system performance and usage reporting. Instances of this class are stored in the initial PegaRULES database schema 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:

The first character of the requestor ID identifies a 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:

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.

The following standard reports are available:

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 tool.

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

Code-Pega-PAL Property

Log-Usage Property

pxDeclarativeRulesInvokedBackgroundCount pxDeclRulesInvokedBckGrdCnt
pxDeclarativeRulesInvokedElapsed pxDeclRulesInvokedElapsed
pxDeclarativeRulesLookupElapsed pxDeclRulesLookupElapsed
pxListRowWithFilteredStreamCount pxListRowWithFilteredStrmCnt
pxListRowWithUnfilteredStreamCount pxListRowWithUnfilteredStrmCnt
pxListWithUnfilteredStreamCount pxListWithUnfilteredStrmCnt
pxSavedClipboardAfterInteractionCount pxSavedCbAfterIntCount
pxSavedClipboardAfterInteractionCPU pxSavedCbAfterIntCPU
pxSavedClipboardAfterInteractionElapsed pxSavedCbAfterIntElapsed
pxSavedContextAfterInteractionCount pxSavedCxtAfterIntCount
pxSavedContextAfterInteractionCPU pxSavedCxtAfterIntCPU
pxSavedContextAfterInteractionElapsed pxSavedCxtAfterIntElapsed

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.

Reporting with the System Management Application

Use the System Management application to report on aggregate system usage based on Log-Usage data, as follows:

  1. Click Designer Studio> System > Operations > System Management Application. You might be prompted for authentication credentials.
  2. Select any node. Your choice does not affect the report contents.
  3. Click Logging and Tracing > Garbage Collector and Log Usage.
  4. Click a radio button to select Log Usage Statistics. Enter a Start Time as five fields, for example Jan, 23, 2006, 16 00 for 16:00 on Jan 23, 2006.
  5. Optionally, enter a Stop Time and Node Name to restrict the report.
  6. Click View.

Trimming the pr_perf_stats table

In a production setting, the pr_perf_stats table can grow to contain millions of rows. By default, the system automatically purges records older than 30 days. If you do not need older rows for performance analysis, debugging, or other reporting, you can purge them by date (known as trimming) without affecting other system capabilities.

Once each day, the Pega-RULES agent starts a stored procedure that purges older rows of this table, passing the value of the pxProcess property as the number of days to retain. To set a retention period longer or shorter than the 30 days, add or revise the following element to your prconfig.xml file and restart the system:

<env name="usage/retentionperiod " value="nnn" />

where nnn is the number of days to retain.

Note: The number of days retained is the number of days plus one. For example, if set to 1, the system keeps two days of data, today and yesterday.

Optionally, you can disable this facility through the Dynamic System Settings data instance Pega-RULES.usage/usagetrackingenabled.