IBM BPM, V8.0.1, All platforms > Tuning > Advanced tuning > Database: general tuning
Provide adequate statistics for optimization
Databases often have a wide variety of available choices when determining the best approach for accessing data. Statistics, which describe the "shape" of the data, can be used to guide the selection of a low-cost data access strategy.
Statistics are maintained on tables and indexes. Examples of statistics include the number of rows in a table and the number of distinct values in a certain column.
Gathering statistics can be expensive, but fortunately, for many workloads, a set of representative statistics allows good performance over a large span of time. It might be necessary to refresh statistics periodically if the data population shifts dramatically.