V$SQL_WORKAREA_ACTIVE contains an instantaneous view of the work areas currently allocated by the system. You can join this view against V$SQL_WORKAREA on WORKAREA_ADDRESS to access the definition of that work area. If a work area spills to disk, then this view contains information for the temporary segment created on behalf of this work area.
The last three columns are included to enable joining V$SQL_WORKAREA_ACTIVE with V$TEMPSEG_USAGE to retrieve more information on this temporary segment.
You can use this view to answer the following:
What are the top 10 largest work areas currently allocated in the system?
What percentage of memory is over-allocated (EXPECTED_SIZE < ACTUAL_MEM_USED) and under-allocated (EXPECTED_SIZE > ACTUAL_MEM_USED)?
What are the active work areas using more memory than what is expected by the memory manager?
What are the active work areas that have spilled to disk?
| Column | Datatype | Description |
|---|---|---|
SQL_HASH_VALUE |
NUMBER |
Hash value of the SQL statement that is currently being executed |
SQL_ID |
VARCHAR2(13) |
SQL identifier of the SQL statement that is currently being executed |
SQL_EXEC_START |
DATE |
Time when the execution of the SQL currently executed by this session started |
SQL_EXEC_ID |
NUMBER |
SQL execution identifier (see V$SQL_MONITOR) |
WORKAREA_ADDRESS |
RAW(4 | 8) |
Address of the work area handle. This is the primary key for the view. |
OPERATION_TYPE |
VARCHAR2(20) |
Type of operation using the work area (SORT, HASH JOIN, GROUP BY, BUFFERING, BITMAP MERGE, or BITMAP CREATE) |
OPERATION_ID |
NUMBER |
A unique number used to identify the operation in the execution plan. This identifier can be joined to V$SQL_PLAN to locate the operation that uses this work area. |
POLICY |
VARCHAR2(6) |
Sizing policy for this work area (MANUAL or AUTO) |
SID |
NUMBER |
Session identifier |
QCINST_ID |
NUMBER |
Query coordinator instance identifier. Along with QCSID, enables you to uniquely identify the query coordinator. |
QCSID |
NUMBER |
Query coordinator session identifier. This is the same as the SID if the work area is allocated by a serial cursor. |
ACTIVE_TIME |
NUMBER |
Average time this work area is active (in microseconds) |
WORK_AREA_SIZE |
NUMBER |
Maximum size (in bytes) of the work area as it is currently used by the operation |
EXPECTED_SIZE |
NUMBER |
Expected size (in bytes) for this work area. EXPECTED_SIZE is set on behalf of the operation by the memory manager. Memory can be over-allocated when WORK_AREA_SIZE has a higher value than EXPECTED_SIZE. This can occur when the operation using this work area takes a long time to resize it. |
ACTUAL_MEM_USED |
NUMBER |
Amount of PGA memory (in bytes) currently allocated on behalf of this work area. This value should range between 0 and WORK_AREA_SIZE. |
MAX_MEM_USED |
NUMBER |
Maximum memory amount (in bytes) used by this work area |
NUMBER_PASSES |
NUMBER |
Number of passes corresponding to this work area (0 if running in OPTIMAL mode) |
TEMPSEG_SIZE |
NUMBER |
Size (in bytes) of the temporary segment used on behalf of this work area. This column is NULL if this work area has not (yet) spilled to disk. |
TABLESPACE |
VARCHAR2(30) |
Tablespace name for the temporary segment created on behalf of this work area. This column is NULL if this work area has not (yet) spilled to disk. |
SEGRFNO# |
NUMBER |
Relative file number within the tablespace for the temporary segment created on behalf of this work area. This column is NULL if this work area has not (yet) spilled to disk. |
SEGBLK# |
NUMBER |
Block number for the temporary segment created on behalf of this work area. This column is NULL if this work area has not (yet) spilled to disk. |
See Also:
Oracle Database Performance Tuning Guide for more information on how to monitor SQL work areas