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Measures reported by OraRollbackTest
The immediate availability of rollback
segments for the various activities that occur in a database server is very
critical. Contention for rollback segments can adversely impact the
performance of a database server and hence, needs to be detected and
reported immediately. To detect contention for rollback segments, the
OraRollbackTest monitors the degree of contention for buffers that contain
rollback segment blocks. The measures
made by this test are as
follows:
| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Pct_system_segment_waits |
Denotes the ratio
of the number of waits for acquiring a header block or a block of the
SYSTEM rollback segment to the total number of requests for data,
measured over a period of time. |
Percent
|
If the number of
waits for any class of block exceeds 1% of the total number of
requests, the size of the SYSTEM rollback segment needs to be
increased. |
| Pct_non_system_segment_waits |
Denotes the ratio
of the number of waits for acquiring a header block or any other block
of a non-SYSTEM rollback segment to the total number of requests for
data, measured over a period of time. |
Percent
|
If the number of
waits for any class of block exceeds 1% of the total number of
requests, the sizes of the existing rollback segments may need to be
increased. Alternatively, additional rollback segments to may be
created to reduce contention. |
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