How To Fix DB6109 - The catalog cache hit ratio is too low

SAP Error Message - Details

• Message type: E = Error

• Message class: DB6 - DB6: Alert Monitoring and Alert Configuration

• Message number: 109

• Message text: The catalog cache hit ratio is too low

What causes this issue?

Too high a proportion of the requested description data for tables from
the DB2 system catalog is not being read using the catalog cache, but
must be read from the database.

System Response

If the hitrate here is low, you should also consider the number of
overflows in the catalog cache. If overflows do in fact occur, this has
an impact on performance.

How to fix this error?

Increase the size of the catalog cache using:
<LB>UPDATE DATABASE CONFIGURATION FOR <SID> USING CATALOGCACHE_SZ
<Value></>
Note that the increased demand for virtual memory causes more paging,
if there is not enough real main memory available.

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

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message DB6109 - The catalog cache hit ratio is too low ?

  The SAP error message DB6109 indicates that the catalog cache hit ratio is too low, which can lead to performance issues in the database. This message typically arises in the context of database performance monitoring and optimization.
  Cause:
  The catalog cache is used by the database to store metadata about database objects (like tables, indexes, etc.) to speed up access to this information. A low catalog cache hit ratio suggests that the database is frequently needing to access the disk to retrieve this metadata instead of being able to retrieve it from the cache. This can be caused by several factors:
  
  Insufficient Cache Size: The cache may not be large enough to hold all the necessary metadata, leading to frequent cache misses.
  High Metadata Activity: If there are many changes to the database schema or a high number of database objects, the cache may be unable to keep up.
  Database Configuration: Incorrect configuration settings for the database cache can lead to suboptimal performance.
  Workload Characteristics: Certain workloads may inherently require more metadata access, leading to a lower hit ratio.
  
  Solution:
  To address the low catalog cache hit ratio, consider the following solutions:
  
  Increase Cache Size: If possible, increase the size of the catalog cache. This can often be done through database configuration settings.
  Optimize Database Configuration: Review and optimize the database configuration settings related to caching. This may involve adjusting parameters that control how much memory is allocated to the catalog cache.
  Monitor and Analyze Workload: Use database monitoring tools to analyze the workload and identify patterns that may be causing excessive metadata access. This can help in understanding whether the workload can be optimized.
  Reduce Metadata Changes: If feasible, reduce the frequency of schema changes or the number of objects being created or modified in the database.
  Database Maintenance: Regularly perform database maintenance tasks, such as updating statistics and reorganizing indexes, which can help improve overall performance.
  
  Related Information:
  
  Monitoring Tools: Use SAP's database monitoring tools or third-party tools to keep an eye on cache hit ratios and other performance metrics.
  Database Documentation: Refer to the documentation for your specific database (e.g., SAP HANA, Oracle, SQL Server) for detailed instructions on configuring cache settings.
  SAP Notes: Check SAP Notes for any specific recommendations or patches related to this error message.
  Performance Tuning: Consider engaging with a database administrator or performance tuning expert if the issue persists, as they can provide tailored solutions based on the specific environment and workload.
  
  By addressing the underlying causes of the low catalog cache hit ratio, you can improve database performance and reduce the likelihood of encountering this error message in the future.