Almost all PowerCenter repository tables use at least one index to speed up queries. Most databases keep and use column distribution statistics to determine which index to use to execute SQL queries optimally. Database servers do not update these statistics continuously.

In frequently used repositories, these statistics can quickly become outdated, and SQL query optimizers might not choose the best query plan. In large repositories, choosing a sub-optimal query plan can have a negative impact on performance. Over time, repository operations gradually become slower.

Informatica identifies and updates the statistics of all repository tables and indexes when you copy, upgrade, and restore repositories. You can also update statistics using the

pmrep UpdateStatistics

command.