Fear No SQL
What is ASH? AWR and Activity Types Average Active Sessions (this page) Graphical Visualizations In the first 2 chapters of this series I queried the ASH data with respect to distinct sample times. While this is helpful maximizing the granularity of the analysis, it can sometimes be too much detail, too many data points for…
What is ASH? AWR and Activity Types (this page) Average Active Sessions Graphical Visualizations Previously I showed a few queries using (G)V$ACTIVE_SESSION_HISTORY, but only mentioned the DBA_HIST_ACTIVE_SESS_HISTORY view. Here I’ll extend the query patterns into this historical repository. Where V$ACTIVE_SESSION_HISTORY is a once-per-second snapshot of sessions from memory and kept in memory, the DBA_HIST_ACTIVE_SESS_HISTORY data…
What is ASH? (this page) AWR and Activity Types Average Active Sessions Graphical Visualizations The Oracle database captures session activity approximately once each second. This data can then be used to identify usage patterns and performance problems. Many performance experts have written very good suites of scripts and tools to query, analyze, and chart the…
Several years ago I made a little math joke about a process that performed millions of look-ups and took forever to complete. That joke, just a short one-liner: “Fast Times Many Equals Slow” has since become a bit of a mantra. The problem can be particularly pernicious in that a problematic set of code might…