V$PGASTAT
provides PGA memory usage statistics as well as statistics about the automatic PGA memory manager when it is enabled (that is, when PGA_AGGREGATE_TARGET
is set). Cumulative values in V$PGASTAT
are accumulated since instance startup.
Column | Datatype | Description |
---|---|---|
NAME |
VARCHAR2(64) |
Name of the statistic (see Table 7-2) |
VALUE |
NUMBER |
Statistic value |
UNIT |
VARCHAR2(12) |
Unit for the value (microseconds, bytes, or percent) |
Table 7-2 V$PGASTAT Statistics
Statistic Name | Description |
---|---|
aggregate PGA target parameter |
Current value of the |
aggregate PGA auto target |
Amount of PGA memory the Oracle Database can use for work areas running in automatic mode. This amount is dynamically derived from the value of the If this value is small compared to the value of |
global memory bound |
Maximum size of a work area executed in automatic mode. This value is continuously adjusted by the Oracle Database to reflect the current state of the work area workload. The global memory bound generally decreases when the number of active work areas is increasing in the system. If the value of the global bound decreases below 1 MB, then the value of |
total PGA allocated |
Current amount of PGA memory allocated by the instance. The Oracle Database attempts to keep this number below the value of the |
total PGA used |
Indicates how much PGA memory is currently consumed by work areas. This number can be used to determine how much memory is consumed by other consumers of the PGA memory (for example, PL/SQL or Java). |
total PGA used for auto workareas |
Indicates how much PGA memory is currently consumed by work areas running under the automatic memory management mode. This number can be used to determine how much memory is consumed by other consumers of the PGA memory (for example, PL/SQL or Java). |
total PGA used for manual workareas |
Indicates how much PGA memory is currently consumed by work areas running under the manual memory management mode. This number can be used to determine how much memory is consumed by other consumers of the PGA memory (for example, PL/SQL or Java). |
over allocation count |
This statistic is cumulative since instance startup. Over allocating PGA memory can happen if the value of If over allocation occurs, then increase the value of |
bytes processed |
Number of bytes processed by memory intensive SQL operators, cumulated since instance startup. |
extra bytes read/written |
Number of bytes processed during extra passes of the input data, cumulated since instance startup. When a work area cannot run optimal, one or more of these extra passes is performed. |
cache hit percentage |
A metric computed by the Oracle Database to reflect the performance of the PGA memory component, cumulative since instance startup. A value of 100% means that all work areas executed by the system since instance startup have used an optimal amount of PGA memory. When a work area cannot run optimal, one or more extra passes is performed over the input data. This will reduce the cache hit percentage in proportion to the size of the input data and the number of extra passes performed. |