When cardinality statistics are automatically updated
For the following operations that you perform on a table, Derby automatically
creates new statistics or updates existing statistics:
When you create a new index on an existing non-empty table. Statistics
are automatically created for only the new index.
When you add a primary key, unique, or foreign key constraint to an existing
non-empty table. If there is no existing index that can be used for the new
key or constraint, Derby automatically
creates statistics for only the new indexes.
When you run the SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure. Statistics
are created automatically for all indexes if the statistics do not already
When you drop a column that is part of a table's index, the statistics
for the affected index are dropped. Statistics are automatically updated for
the other indexes on the table.