The number of times a buffer
pool index page was physically
written to disk by either an asynchronous page cleaner, or a prefetcher.
A prefetcher may have written dirty pages to disk to make space for
the pages being prefetched.
Table 2. Snapshot
Monitoring InformationSnapshot Level |
Logical Data Grouping |
Monitor
Switch |
Database |
dbase |
Buffer
Pool |
Table Space |
tablespace |
Buffer Pool |
Buffer Pool |
bufferpool |
Buffer Pool |
For snapshot
monitoring, this counter can be reset.
Table 3. Event Monitoring InformationEvent Type |
Logical
Data Grouping |
Monitor Switch |
Database |
event_db |
- |
Tablespaces |
event_tablespace |
- |
Usage
You
can use this element with the
pool_index_writes monitor
element to calculate the number of physical index write requests that
were performed synchronously (that is, physical index page writes
that were performed by
database
manager agents).
Use the following formula:
pool_index_writes - pool_async_index_writes
By comparing the ratio of asynchronous to synchronous writes, you
can gain insight into how well the buffer pool page cleaners are performing.
This ratio can be helpful when you are tuning the num_iocleaners
configuration parameter.