Is it possible to create an index on a field that does not contain unique values?

Yes, it is possible to create an index on a field that does not contain unique values. Such indexes are called non-unique indexes and are used to speed up search and sorting on a field where values may repeat.

For example, in a database, you can create an index on the "status" field, where many records have the same value "active." The index will help quickly find all records with this status, despite the repeating values.

Unique indexes require the values in the field to be unique, whereas non-unique indexes do not have such restrictions.