ASOSAMPLESIZEPERCENT

Specifies the number of cells sampled from the input-level data. The sampled data is used to estimate the size of aggregate views. Larger sample sizes enable Essbase to make increasingly accurate estimates of average view sizes. View selection using a larger sample size enables Essbase to more closely meet the stop size.

Sample sizes are specified as a percentage of input-level data.

Syntax

ASOSAMPLESIZEPERCENT [appname [dbname]] n

Performance Impact

Estimates using larger sample sizes take longer to complete, which may have a significant performance impact on view selection. The recommendation for a database with more than 1 billion input-level cells is to start with a small setting such as 0.1 (meaning 0.1%). Slowly increase this setting until the preferred trade-off between view selection performance and accuracy is reached. The optimal setting for a database with more than 1 billion cells will probably be less than 3%. See “Performance Improvement When Building Aggregate Views on Aggregate Storage Databases” in the Oracle Essbase Database Administrator's Guide.

To gauge the accuracy of view size estimates for aggregate views that have been built, use the following MaxL command:

query database appname.dbname list existing_views

Compare the values in the columns named size_ratio_estimate and size_ratio_actual. The accuracy of each view size estimate differs for each aggregate view.

Example

ASOSAMPLESIZEPERCENT ASOsamp.Sample 1