Configure OpenAPI OData 4․0 response limits to prevent 503 errors

Products

• Network Observability

Issue/Introduction

Adjusting the OpenAPI for OData 4․0 configuration limits, such as defaultTopLimit, is required to return more than the default 50 results per query ․​​​​​‌​‍

ERROR MESSAGE (if applicable): "503 Service Unavailable"

SYMPTOMS:

• OData queries return only 50 devices by default ․

• Increasing the limit to 20,000 per page causes severe performance degradation and memory pressure on the Portal ․

• Changes to com․ca․im․odata․beans․ODataLimiters․cfg do not reflect in the user interface ․

CONTEXT: After upgrading to release 25․4․5 and moving to OData 4․0, limits must be configured correctly to retrieve large datasets without impacting system stability ․

IMPACT: Users cannot access complete device lists in single queries, and misconfiguration leads to Portal memory exhaustion ․

Environment

DX NetOps Performance Management 25.4.5

Cause

Setting the defaultTopLimit to an excessively high number causes memory pressure on the Portal, leading to 503 Service Unavailable errors ․ Additionally, modifying the incorrect configuration file prevents the limit changes from taking effect ․

Resolution

STEPS:

Step 1․ UPDATE THE ODATA 4․0 PROPERTIES FILE

Path: /opt/IMDataAggregator/config/com․ca․im․odata․beans․OData4Properties․cfg

Modify the defaultTopLimit parameter to the desired value ․

EXPECTED: The configuration updates take effect in real-time immediately after saving the file ․ NOTE: Do not recycle or restart the Data Aggregator service; a restart is not required for this change ․

Step 2․ USE THE COUNT ENDPOINT FOR LARGE DATASETS

To avoid memory pressure and 503 errors on the Portal, use the $count endpoint instead of retrieving full entity data for large queries ․

Path: http://[hostname]:8181/pc/odata4/api/components/$count?$filter=contains(Name, 'CPU')

EXPECTED: The query returns the total number of entities matching the filter without overwhelming the Portal memory ․

Additional Information

RELATED RESOURCES:

• Documentation: Configure OpenAPI Defaults and Limits

• Release Notes: Features and Enhancements OData4

KNOWN LIMITATIONS:

• A high limit per page can cause significant performance degradation ․

VERSION NOTES:

• v25․4․6+: Enhancement to QueryBuilder 4 allows creating queries that return a specific number of entities using the $count endpoint ․