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

The key (pzInsKey column) of the pr_perf_stats table — the key of each Log-Usage instance — is concatenated from the values of 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 four values:

• INTERVAL — Records cumulative usage statistics for a requestor as of the end of an interval (typically a clock hour).
• PASSIVATE — Records passivation of a requestor, such as occurs when a session times out. The PersistRequestor setting in the prconfig.xml file controls passivation.
• TERMINATED — Records log-out, forced timeout, or other termination of a requestor.
• ACTIVATE — Records reactivation of a passivated requestor.

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 Agent Queue form for the Pega-RULES agent.

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

A daemon known as the 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 may 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 exposed 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 tool. For a listing and brief descriptions of those properties, see Performance tool — Full details display.

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

Summary View report

Run the standard summary view report Log-Usage.BrowseUsageStatistics.ALL to review the types of data in this table. (Summary view reports are limited to 10,000 records; only the first 10,000 rows in the table that meet your selection criteria appear.) You can copy this summary view report and customize your copy.

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

1. Select Tools > System Management Application in the Developer portal. You may be prompted for authentication credentials.
2. The System Management application starts. Select any node; your choice does not affect the report contents.
3. Select 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 the top  VIEW   button.

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.

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

In releases before V5.2, instances of the Log-Usage class were stored in the pr4_log_usage table. The pr4_log_usage database table is not used in Version 5.2 or later. A separate table, pr4_log_rule_usage, supports the Log-RuleUsage class.