DBAHIST

DBAHIST is a term commonly used to refer to Oracle Database’s historical performance data, exposed through a family of data dictionary views prefixed with DBA_HIST_. It represents the stored history of performance-related metrics gathered by the Automatic Workload Repository (AWR) and related components, rather than a single table or view. The DBA_HIST_ views provide a historical record of system and session activity that enables trend analysis, bottleneck identification, and capacity planning.

Key components and scope

The DBA_HIST family typically includes views such as DBA_HIST_SNAPSHOT, which contains time-stamped snapshots of the database state; DBA_HIST_SYSSTAT and DBA_HIST_OSSTAT for historical system and operating system statistics; DBA_HIST_SQLSTAT for historical SQL execution statistics; and DBA_HIST_ACTIVE_SESS_HISTORY for historical sampled session activity. These views collectively cover workload, resource usage, wait events, and SQL performance over defined intervals. Data are gathered at regular snapshots and stored in the AWR repository, with additional history captured through ASH-derived views.

Access and licensing

Access to DBA_HIST views is available when the Oracle Diagnostic Pack is licensed, and entry points are provided via SQL queries against the DBA_HIST_ views. Queries typically require joining with DBA_HIST_SNAPSHOT to map statistics to time periods. Data retention is configurable and depends on licensing, storage, and organizational policies.

Usage and limitations

DBAHIST enables retrospective analysis, performance forecasting, and capacity planning by providing historical context for performance metrics. Limitations include the need for proper licensing, the reliance on scheduled snapshots, and the potential volume of historical data requiring archive and maintenance strategies.

See also

Oracle Database, Automatic Workload Repository (AWR), Active Session History (ASH), DBA views, V$ views.