Tohuwabohu excorcism

is a secondary DB key that you can optionally decide to use alongside your Partition Key.

if you decide to only specify a partition key and not a sort key, all records must have a unique partition key value. In other words, you will only be able to have one record with CustomerId as CID-123.

By using a Sort key, we’re also able to perform what I call “range-like” queries on our Sort Key values.

• = (equal to)
• ⇐ (less than equal to)
• >= (greater than equal to)
• > (greater than)
• between
• begins with
• sort ascending / descending

Local Secondary Index is like an additional sort-key.
Relies on Partition Key.
You can have max. 5 of LSI.

• partitionKey+sortKey1
• partitionKey+sortKey2
• .. partitionKey+sortKey6.

https://stackoverflow.com/questions/21381744/difference-between-local-and-global-indexes-in-dynamodb

Facts:

• Limit you to only 10GB of data per Partition Key.
• Unlike GSIs, they share throughput with base table.
  
  If you query for data using LSI, the usage will be calculated against capacity of the underlying table and its base index.
• They have to be specified at table creation. you can't add or remove them after provisioning the table

DynamoDB global secondary index is a type of index containing a partition key and a sort key different from the base table's primary key.

It is known as the “global” secondary index since the queries on the index can access data from multiple partitions of the base table.