What types of comparisons are not implemented in database hash indexes?

Hash indexes in databases are optimized for exact key lookups using a hash function. Because of this, they do not support the following types of comparisons:

• Range queries (e.g., >, <, BETWEEN)
• Partial matches (e.g., LIKE with patterns)
• Sorting by key

This is because a hash index does not store data in sorted order, but distributes it into buckets based on the hash. For such queries, B-trees or other types of indexes are usually used.