How To Fix D4518 - Average time used by table scans (s)

SAP Error Message - Details

• Message type: E = Error

• Message class: D4 - DB2/400 specific messages

• Message number: 518

• Message text: Average time used by table scans (s)

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message D4518 - Average time used by table scans (s) ?

  The SAP error message D4518, which refers to "Average time used by table scans (s)," is typically related to performance issues in the SAP system, particularly concerning database table scans. This message indicates that the average time taken for table scans is higher than expected, which can lead to performance degradation in the system.
  Cause:
  
  Inefficient Queries: Queries that do not use indexes effectively may result in full table scans, which are time-consuming.
  Lack of Indexes: If the relevant database tables do not have appropriate indexes, the database engine may need to scan the entire table to retrieve the required data.
  Database Statistics: Outdated or missing database statistics can lead to suboptimal query execution plans.
  High Volume of Data: Large tables with a significant amount of data can naturally lead to longer scan times.
  Database Configuration: Poorly configured database parameters can also contribute to performance issues.
  
  Solution:
  
  Optimize Queries: Review and optimize SQL queries to ensure they are using indexes effectively. This may involve rewriting queries or adding WHERE clauses to limit the data being scanned.
  Create/Update Indexes: Analyze the database tables and create or update indexes on columns that are frequently used in WHERE clauses or JOIN conditions.
  Update Database Statistics: Regularly update database statistics to ensure the query optimizer has the most current information to create efficient execution plans.
  Partitioning: For very large tables, consider partitioning the tables to improve performance and reduce scan times.
  Database Tuning: Review and adjust database configuration settings to optimize performance based on the specific workload and usage patterns.
  Monitoring and Analysis: Use performance monitoring tools to analyze query performance and identify bottlenecks. Tools like SAP's SQL Trace (ST05) can help in identifying problematic queries.
  
  Related Information:
  
  Transaction Codes: Use transaction codes like ST04 (Database Performance Analysis) and ST05 (SQL Trace) to monitor and analyze database performance.
  SAP Notes: Check SAP Notes for any specific recommendations or patches related to performance issues.
  Database Administration: Engage with your database administrator (DBA) for deeper analysis and assistance in optimizing database performance.
  Performance Tuning Guides: Refer to SAP's performance tuning guides for best practices on optimizing SAP systems and databases.
  
  By addressing the underlying causes of the D4518 error message, you can improve the performance of your SAP system and reduce the average time used by table scans.