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Oracle® Database Reference 10g Release 2 (10.2) Part Number B14237-02 |
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# DBA_HIST_ACTIVE_SESS_HISTORY

`DBA_HIST_ACTIVE_SESS_HISTORY` displays the history of the contents of the in-memory active session history of recent system activity. This view contains snapshots of `V$ACTIVE_SESSION_HISTORY`. See "V$ACTIVE_SESSION_HISTORY" for further interpretation details for many of these columns (except `SNAP_ID`, `DBID`, and `INSTANCE_NUMBER`).

Column | Datatype | NULL | Description
--- | --- | --- | ---
`SNAP_ID` | `NUMBER` |  | Unique snapshot ID
`DBID` | `NUMBER` |  | Database ID for the snapshot
`INSTANCE_NUMBER` | `NUMBER` |  | Instance number for the snapshot
`SAMPLE_ID` | `NUMBER` |  | ID of the sample
`SAMPLE_TIME` | `TIMESTAMP(3)` |  | Time of the sample
`SESSION_ID` | `NUMBER` |  | Session identifier
`SESSION_SERIAL#` | `NUMBER` |  | Session serial number (used to uniquely identify a session's objects)
`USER_ID` | `NUMBER` |  | Oracle user identifier
`SQL_ID` | `VARCHAR2(13)` |  | SQL identifier of the SQL statement that is currently being executed
`SQL_CHILD_NUMBER` | `NUMBER` |  | Child number of the SQL statement that is currently being executed
`SQL_PLAN_HASH_VALUE` | `NUMBER` |  | Numerical representation of the SQL plan for the cursor
`FORCE_MATCHING_SIGNATURE` | `NUMBER` |  | The signature used when the `CURSOR_SHARING` parameter is set to `FORCE`
`SQL_OPCODE` | `NUMBER` |  | Indicates what phase of operation the SQL statement is in
`SERVICE_HASH` | `NUMBER` |  | Hash that identifies the Service
`SESSION_TYPE` | `VARCHAR2(10)` |  | Session type: `FOREGROUND` `BACKGROUND`
`SESSION_STATE` | `VARCHAR2(7)` |  | Session state: `WAITING` `ON` `CPU`
`QC_SESSION_ID` | `NUMBER` |  | Query coordinator session ID
`QC_INSTANCE_ID` | `NUMBER` |  | Query coordinator instance ID
`BLOCKING_SESSION` | `NUMBER` |  | Session identifier of the blocking session. Populated only when the session was waiting for enqueues or a "buffer busy" wait. Maps to `V$SESSION.BLOCKING_SESSION`.
`BLOCKING_SESSION_STATUS` | `VARCHAR2(11)` |  | Status of the blocking session: `VALID` `NO HOLDER` `GLOBAL` `NOT IN WAIT` `UNKNOWN`
`BLOCKING_SESSION_SERIAL#` | `NUMBER` |  | Serial number of the blocking session
`EVENT` | `VARCHAR2(64)` |  | If `SESSION_STATE = WAITING`, then the event for which the session was waiting at the time of sampling. If `SESSION_STATE = ON CPU`, then this column will be NULL.
`EVENT_ID` | `NUMBER` |  | Identifier of the resource or event for which the session is waiting or for which the session last waited
`SEQ#` | `NUMBER` |  | Sequence number that uniquely identifies the wait (incremented for each wait)
`P1TEXT` | `VARCHAR2(64)` |  | Text of first additional parameter
`P1` | `NUMBER` |  | First additional parameter
`P2TEXT` | `VARCHAR2(64)` |  | Text of second additional parameter
`P2` | `NUMBER` |  | Second additional parameter
`P3TEXT` | `VARCHAR2(64)` |  | Text of third additional parameter
`P3` | `NUMBER` |  | Third additional parameter
`WAIT_CLASS` | `VARCHAR2(64)` |  | Wait class name of the event for which the session was waiting at the time of sampling. Interpretation is similar to that of the `EVENT` column. Maps to `V$SESSION.WAIT_CLASS`.
`WAIT_CLASS_ID` | `NUMBER` |  | Wait class identifier of the event for which the session was waiting at the time of sampling. Interpretation is similar to that of the `EVENT` column. Maps to `V$SESSION.WAIT_CLASS_ID`.
`WAIT_TIME` | `NUMBER` |  | Total wait time for the event for which the session last waited (`0` if currently waiting)
`TIME_WAITED` | `NUMBER` |  | Time that the current session actually spent waiting for the event. This column is set for waits that were in progress at the time the sample was taken.
`XID` | `RAW(8)` |  | Transaction ID that the session was working on at the time of sampling. `V$SESSION` does not contain this information.
`CURRENT_OBJ#` | `NUMBER` |  | Object ID of the object that the session is currently referencing. This information is only available if the session was waiting for Application, Cluster, Concurrency, and User I/O wait events. Maps to `V$SESSION.ROW_WAIT_OBJ#`.
`CURRENT_FILE#` | `NUMBER` |  | File number of the file containing the block that the session is currently referencing. This information is only available if the session was waiting for Cluster, Concurrency, and User I/O wait events. Maps to `V$SESSION.ROW_WAIT_FILE#`.
`CURRENT_BLOCK#` | `NUMBER` |  | ID of the block that the session is currently referencing
`PROGRAM` | `VARCHAR2(48)` |  | Name of the operating system program
`MODULE` | `VARCHAR2(48)` |  | Name of the currently executing module as set by the `DBMS_APPLICATION_INFO.SET_MODULE` procedure
`ACTION` | `VARCHAR2(32)` |  | Name of the currently executing action as set by the `DBMS_APPLICATION_INFO.SET_ACTION` procedure
`CLIENT_ID` | `VARCHAR2(64)` |  | Client identifier of the session