How to detect when the size of a BLOB column read exceeds a threshold (PEGA0039 alert)
This alert is generated when a database query retrieves a BLOB (pzPVStream property value) that is larger (in bytes) than the threshold value. The alert provides a warning that memory performance of your system may be hurt when PRPC expands the BLOB onto a clipboard page.
In contrast to this alert, the similar PEGA0004 alert indicates the size of the entire result set of a query, that may or may not include a BLOB in the individual rows.
Alert log message
The alert identifies the pzInsKey that was read, and the size in bytes of the BLOB:
Read blob from database with compressed size 2058486 expanded size 4125916. pzInsKey: RULE-FILE-BINARY WEBWB OPENAUTHORING!CAB #20100304T152007.144 GMT
Modifying the alert settings
You can modify the default settings in the alerts section of the prconfig.xml file, as follows:
- Open the
prconfig.xmlfile and update these alerts entries:
enabled
<env name = “alerts/database/blobsizeread/enabled" value="true" />
The enabled value is a boolean. To turn off the alert, "false"
threshold
<env name = “alerts/database/blobsizeread/threshold" value="3" />
The threshold value is a positive integer in megabytes (default is 3). This is checked against the compressed size of the BLOB being read.
- Stop and restart the server.
As an alternative to the prconfig.xml file, you can use Dynamic System Settings to configure your application.
See How to create or update a prconfig setting.
Next steps
Examine the record being read (identified by the pzInsKey value and determine if the entire BLOB is needed. Usually, you can break the data into additional logical segments (as dictated by your application). This alert is often related to PEGA0004 and PEGA0025 alerts.
Related PDN articles
Consult these PDN 
articles:
- 25335 Understanding the PEGA0004 Alert
- 25362 Understanding the PEGA0025 Alert
- 23116 How to detect and remedy the performance impact of Obj-List methods and List View reports
SysAdmin category