The character or characters used to denote hierarchy.
In order to flatten out structures such as Maps and List attributes in DynamoDB, we need some specifier that states what the separation is between those columns and other columns. If this value is "." and a column comes back with the name address.city, this indicates that there is a mapped attribute with a child called city. If your data has columns that already use a single period within the attribute name, set the SeparatorCharacter to a different character or characters.