How To Fix DB11168 - Wait event 'db file sequential read'

SAP Error Message - Details

• Message type: E = Error

• Message class: DB11 - Oracle Monitor: messages

• Message number: 168

• Message text: Wait event 'db file sequential read'

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message DB11168 - Wait event 'db file sequential read' ?

  The SAP error message DB11168, which indicates a wait event for 'db file sequential read', is related to performance issues in the database, particularly in Oracle databases. This wait event typically occurs when a session is waiting for a single block read from disk into memory. It is often associated with queries that are accessing indexed data or performing operations that require reading data from the database.
  Cause:
  
  Inefficient Queries: Poorly optimized SQL queries can lead to excessive waits for data retrieval.
  Indexing Issues: Missing or fragmented indexes can cause the database to perform more disk reads than necessary.
  High I/O Load: If the database server is under heavy load, it may struggle to read data efficiently.
  Database Configuration: Suboptimal database configuration settings can lead to increased wait times.
  Data Skew: Uneven distribution of data can lead to certain blocks being accessed more frequently, causing contention.
  
  Solution:
  
  Optimize SQL Queries: Review and optimize the SQL queries that are causing the wait events. Use tools like the Oracle SQL Tuning Advisor to identify and fix performance issues.
  Check Indexes: Ensure that the necessary indexes are in place and are not fragmented. Rebuild or reorganize indexes if needed.
  Monitor I/O Performance: Use performance monitoring tools to analyze I/O performance and identify bottlenecks. Consider upgrading hardware if necessary.
  Database Configuration: Review and adjust database parameters related to memory allocation, I/O settings, and parallel processing to improve performance.
  Analyze Execution Plans: Use the EXPLAIN PLAN command to analyze how queries are executed and identify any inefficiencies.
  Partitioning: If applicable, consider partitioning large tables to improve access times and reduce contention.
  Caching: Increase the size of the buffer cache to reduce the need for disk reads.
  
  Related Information:
  
  Oracle Wait Events: Understanding Oracle wait events can help diagnose performance issues. The 'db file sequential read' wait event is common in environments with heavy read operations.
  Performance Monitoring Tools: Tools like Oracle Enterprise Manager, AWR (Automatic Workload Repository), and ASH (Active Session History) reports can provide insights into wait events and overall database performance.
  SAP Notes: Check SAP Notes for any specific recommendations or patches related to performance issues in your version of SAP.
  Database Statistics: Regularly gather and analyze database statistics to ensure the optimizer has the most accurate information for query execution.
  
  By addressing the underlying causes of the 'db file sequential read' wait event, you can improve the performance of your SAP system and reduce the occurrence of this error message.