In most respects, a hash index is similar to a base table. For example, you can perform COLLECT STATISTICS, DROP STATISTICS, HELP, and SHOW statements on a hash index.
Unlike base tables, you cannot do the following things with hash indexes:
- Query or update hash index rows explicitly.
- Store and maintain arbitrary query results such as expressions.
- Create explicit unique indexes on its columns.
- Partition the primary index of the hash index.