Local Secondary Index (LSI)
- Alternative Sort Key for your table (same Partition Key as that of base table)
- The Sort Key consists of one scalar attribute (String, Number, or Binary)
- Up to 5 Local Secondary Indexes per table
- Must be defined at table creation time
Global Secondary Index (GSI)
- Alternative Primary Key (HASH or HASH+RANGE) from the base table
- Speed up queries on non-key attributes
- The Index Key consists of scalar attributes (String, Number, or Binary)
- Attribute Projections - some or all the attributes of the base table (KEYS_ONLY, INCLUDE, ALL)
- Must provision RCUs & WCUs for the index
- Can be added/modified after table creation