How to estimate the size of an Oracle Performance Warehouse Database (PMDB).

by Oct 7, 2014

When Precise is initially installed, instances added or data retention parameters can be modified via AdminPoint. It is often
desirable to estimate the size to which the Performance Warehouse Database will grow so that necessary resources, i.e. storage,
can be allocated.

The size of the PMDB is determined not only by the data retention policy, but also by the amount of activity and the size of the
environment (how many instances are being monitored). If activity on the monitored instances is not relatively constant, it is
extremely difficult to assess the growth of the PMDB. However, assuming that activity is relatively constant, the size of the PMDB will initially experience a sudden growth in size. Once the retention period has been met, the growth of the PMDB should then plateau and remain relatively constant.  Based on the retention and purge parameters, it may take 3 years for the growth of the PMDB to stablize.

The weekly (_W) and monthly (_M) statistics tables are primarily partitioned by month, and the timeslice (_T) and daily (_D)
partitioned by weeks. They are then normally sub-partitioned by the monthly/weekly timestamp and instance. Therefore, in the
situation when activity is relatively constant, it is possible to estimate the final size of the statistics tables. For example,
if after 3 months the average size of a specific table is 100mb, it is reasonable to assume that after 6 months, will be 200mb,
and so on.

For more information about the sizing of the PMDB, Precise customers should check the Precise portal at  A valid user id and password is required.