Support Article
Poor performance when using ADM queries without Where condition
SA-72468
Summary
Pega Marketing 7.4 is installed on Pega 7.4.
Pega 7.4 is configured with an external Cassandra with a cluster of more than 30 nodes. The existing external Cassandra cluster has more than five existing non-Pega applications.
PEGA0075 alerts are generated for Cassandra queries without the Where clause and performance degrades. This occurs when using queries generated by Pega to Adaptive Decision Manager (ADM) keyspaces. The following are the identified queries:
- select(nid).distinct().from(adm_commitlog, adm_active_nodes);
- select(p, nid).from(adm_commitlog, adm_response_meta_info);
- select distinct fk from dcw_adm.adm_scoringmodel;
- select(fk).distinct().from(adm, adm_factory_handled_responses);
- select distinct nid from adm_commitlog.adm_active_nodes;
Error Messages
Not Applicable
Steps to Reproduce
Run the Decision application that uses the ADM.
Root Cause
A defect in Pegasystems’ code or rules.
The queries without the Where condition perform a table scan. As a result, performance degrades for all applications that use the same Cassandra cluster. This is because these queries tie up the coordinator node for the query duration across the entire cluster.
Resolution
Apply HFix-49085.
Published March 19, 2019 - Updated December 2, 2021
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