# When cardinality statistics go stale

As you saw in When cardinality statistics are automatically updated, cardinality statistics are automatically updated only in limited cases. Normal insert, update, and delete statements do not cause the statistics to be updated. This means that statistics can go stale. Stale statistics can slow your system down, because they worsen the accuracy of the optimizer's estimates of selectivity.

Parent topic: Working with cardinality statistics
Related concepts
When cardinality statistics are automatically updated