Index Properties

In addition to the numerous index typesMongoDB supports, indexes can also have various properties. Thefollowing documents detail the index properties that you can selectwhen building an index.

• TTL Indexes
• The TTL index is used for TTL collections, which expire data aftera period of time.
• Unique Indexes
• A unique index causes MongoDB to reject all documents that containa duplicate value for the indexed field.
• Partial Indexes
• A partial index indexes only documents that meet specified filtercriteria.
• Case Insensitive Indexes
• A case insensitive index disregards the case of the index keyvalues.
• Sparse Indexes
• A sparse index does not index documents that do not have theindexed field.