https://www.oraclescripts.com/tags/awr-retention/Recent content in AWR Retention on Oracle ScriptsHugo -- gohugo.ioenOracleScripts.comWed, 07 Oct 2026 00:00:00 +0000https://www.oraclescripts.com/post/query-historical-ash-beyond-memory-dba-hist-active-sess-history/Wed, 07 Oct 2026 00:00:00 +0000https://www.oraclescripts.com/post/query-historical-ash-beyond-memory-dba-hist-active-sess-history/ <h2 id="query-historical-ash-beyond-memory-with-dba_hist_active_sess_history">Query Historical ASH Beyond Memory with DBA_HIST_ACTIVE_SESS_HISTORY</h2> <h2 id="purpose">Purpose</h2> <p>Troubleshooting a performance spike after the fact is a different job than watching one happen live. By the time anyone opens a session the next morning to ask what was running during last night's batch window, the in-memory <strong><a href="https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/V-ACTIVE_SESSION_HISTORY.html">V$ACTIVE_SESSION_HISTORY</a></strong> buffer may already have cycled past that exact window. <strong><a href="https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/DBA_HIST_ACTIVE_SESS_HISTORY.html">DBA_HIST_ACTIVE_SESS_HISTORY</a></strong> is where that same sampled activity keeps existing — Oracle's own reference documentation describes it as the view that &quot;displays the history of the contents of the in-memory active session history of recent system activity,&quot; built from snapshots of the live view taken before the buffer discards them.</p>