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
exist.
- 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.
