How To Fix RSDBMAN004 - - Parallel subaccesses ended; serial accesses exist

SAP Error Message - Details

• Message type: E = Error

• Message class: RSDBMAN -

• Message number: 004

• Message text: - Parallel subaccesses ended; serial accesses exist

What causes this issue?

All subaccesses that can be processed in parallel are processed. Some
subaccesses to be processed sequentially remain. This is described in
the documentation on processing queries under <ZK>Partial Parallel
Processing</>.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message RSDBMAN004 - - Parallel subaccesses ended; serial accesses exist ?

  The SAP error message RSDBMAN004 - Parallel subaccesses ended; serial accesses exist typically occurs in the context of data extraction or reporting processes, particularly when using the SAP BW (Business Warehouse) or SAP HANA systems. This error indicates that while the system attempted to execute parallel data accesses, it encountered some serial accesses that prevented it from fully utilizing parallel processing capabilities.
  Cause:
  
  Data Locking: The presence of locks on certain data records can force the system to revert to serial processing for those records.
  Data Model Configuration: Certain configurations in the data model or queries may not support parallel processing.
  Resource Constraints: Limited system resources (CPU, memory) can lead to a fallback to serial processing.
  Query Design: Inefficient query design or complex joins can lead to serial execution paths.
  Database Configuration: The underlying database settings may not be optimized for parallel processing.
  
  Solution:
  
  Check Locks: Investigate if there are any locks on the data being accessed. You can use transaction codes like SM12 to check for locks and resolve them if necessary.
  Optimize Queries: Review and optimize the queries or data models to ensure they are designed for parallel processing. Simplifying complex joins or breaking down large queries can help.
  Adjust Database Settings: Ensure that the database is configured to allow for parallel processing. This may involve adjusting parameters related to parallel execution.
  Monitor System Resources: Check system performance and resource utilization. If the system is under heavy load, consider scaling resources or scheduling heavy jobs during off-peak hours.
  Update Statistics: Ensure that database statistics are up to date, as outdated statistics can lead to inefficient query plans.
  SAP Notes: Check for any relevant SAP Notes or patches that may address this issue. SAP frequently releases updates that can resolve known issues.
  
  Related Information:
  
  Transaction Codes: Familiarize yourself with transaction codes like ST22 (Dump Analysis), SM21 (System Log), and ST03N (Workload Analysis) to diagnose performance issues.
  SAP BW/4HANA: If you are using SAP BW/4HANA, ensure that you are following best practices for data modeling and query design specific to that environment.
  Documentation: Refer to SAP Help documentation for detailed guidance on optimizing performance and troubleshooting errors related to data access.
  
  If the issue persists after trying the above solutions, it may be beneficial to consult with SAP support or your technical team for further investigation.