V$ACTIVE_SESSION_HISTORY

V$ACTIVE_SESSION_HISTORY displays sampled session activity in the database. It contains snapshots of active database sessions taken once a second. A database session is considered active if it was on the CPU or was waiting for an event that didn't belong to the Idle wait class. Refer to the V$EVENT_NAME view for more information on wait classes.

This view contains one row for each active session per sample and returns the latest session sample rows first. A majority of the columns describing the session in the active session history are present in the V$SESSION view.

Column	Datatype	Description
`SAMPLE_ID`	`NUMBER`	ID of the sample
`SAMPLE_TIME`	`TIMESTAMP(3)`	Time at which the sample was taken
`SESSION_ID`	`NUMBER`	Session identifier; maps to `V$SESSION.SID`
`SESSION_SERIAL#`	`NUMBER`	Session serial number (used to uniquely identify a session's objects); maps to `V$SESSION.SERIAL#`
`USER_ID`	`NUMBER`	Oracle user identifier; maps to `V$SESSION.USER#`
`SQL_ID`	`VARCHAR2(13)`	SQL identifier of the SQL statement that the session was executing at the time of sampling
`SQL_CHILD_NUMBER`	`NUMBER`	Child number of the SQL statement that the session was executing at the time of sampling
`SQL_PLAN_HASH_VALUE`	`NUMBER`	Numerical representation of the SQL plan for the cursor. This information might not be available for all session samples. `V$SESSION` does not contain this information.
`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 was in; maps to `V$SESSION.COMMAND` See Also: "V$SESSION" for information on interpreting this column
`SERVICE_HASH`	`NUMBER`	Hash that identifies the Service; maps to `V$ACTIVE_SERVICES.NAME_HASH`
`SESSION_TYPE`	`VARCHAR2(10)`	Session type: `FOREGROUND` `BACKGROUND`
`SESSION_STATE`	`VARCHAR2(7)`	Session state: `WAITING` `ON CPU`
`QC_SESSION_ID`	`NUMBER`	Query coordinator session ID. This information is only available if the sampled session is a parallel query slave. For all other sessions, the value is `0`.
`QC_INSTANCE_ID`	`NUMBER`	Query coordinator instance ID. This information is only available if the sampled session is a parallel query slave. For all other sessions, the value is `0`.
`BLOCKING_SESSION`	`NUMBER`	Session identifier of the blocking session. Populated only when the session was waiting for enqueues or a "buffer busy" wait. Maps to `V$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 for at the time of sampling. If `SESSION_STATE` = `ON CPU`, then this column will be NULL. See Also: Appendix C, "Oracle Wait Events"
`EVENT_ID`	`NUMBER`	Identifier of the resource or event for which the session is waiting or for which the session last waited. Interpretation is similar to that of the `EVENT` column.
`EVENT#`	`NUMBER`	Number of the resource or event for which the session is waiting or for which the session last waited. Interpretation is similar to that of the `EVENT` column.
`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`	`0` if the session was waiting at the time of sampling Total wait time for the event for which the session last waited if the session was on the CPU when sampled Whether or not `WAIT_TIME` = `0` is what is useful to find the `SESSION_STATE` at the time of sampling, rather than the actual value of `WAIT_TIME` itself. `Maps to V$SESSION.WAIT_TIME`.
`TIME_WAITED`	`NUMBER`	If `SESSION_STATE` = `WAITING`, then the time that the session actually spent waiting for that EVENT. This column is set for waits that were in progress at the time the sample was taken. If a wait event lasted for more than a second and was caught waiting in more than one session sample row, then the actual time spent waiting for that wait event will be populated in the last of those session sample rows. At any given time, this information will not be available for the latest session sample.
`XID`	`RAW(8)`	Transaction ID that the session was working on at the time of sampling. `V$SESSION` does not contain this information.
`CURRENT_OBJ#`	`NUMBER`	Object ID of the object that the session is referencing. This information is only available if the session was waiting for Application, Cluster, Concurrency, and User I/O wait events. Maps to `V$SESSION.ROW_WAIT_OBJ#`.
`CURRENT_FILE#`	`NUMBER`	File number of the file containing the block that the session is referencing. This information is only available if the session was waiting for Cluster, Concurrency, and User I/O wait events. Maps to `V$SESSION.ROW_WAIT_FILE#`.
`CURRENT_BLOCK#`	`NUMBER`	ID of the block that the session is referencing. This information is only available if the session was waiting for Cluster, Concurrency, and User I/O wait events. Maps to `V$SESSION.ROW_WAIT_BLOCK#`.
`PROGRAM`	`VARCHAR2(48)`	Name of the operating system program
`MODULE`	`VARCHAR2(48)`	Name of the executing module when sampled, as set by the `DBMS_APPLICATION_INFO.SET_MODULE` procedure
`ACTION`	`VARCHAR2(32)`	Name of the executing module when sampled, as set by the `DBMS_APPLICATION_INFO.SET_ACTION` procedure
`CLIENT_ID`	`VARCHAR2(64)`	Client identifier of the session; maps to `V$SESSION.CLIENT_IDENTIFIER`