Part II: Further Adventures in Active Session History

OUG Scotland, 11.6.2020

  • This the second of two presentations about Active Session History (ASH).  ASH can tell you far more than simply how much time was spent in a particular SQL statement. This presentation shows how to deal with some of the challenges of manipulating ASH data and various ways to use it to investigate performance problems.  Including:
    • Dealing with the consequences of literal values in SQL, Adaptive Plans, multi-node RAC systems, Adaptive Plans, and analysis of PL/SQL.
    • Tracking temporary tablespace and PGA utilisation.
    • Analysis of the effectiveness of parallelism. 
    • Analysis of sources of I/O. 
    • Tracking transactions and executions. 
    • Some of the things that can go wrong with ASH and AWR, and how to work around them.