Concept TL;DR: DB consists of tables, and items in table have sort of “kay-value”. The main contents (attributes, ~values of key-value) is json. Table In table, we put items. Each items has “attributes”. Every items must have a “partition key (or primary key)” attribute. Each items could have “sort key” attribute. “We can think of the parition as a folder/bucket which contains items. And the sort key orders the items within the folder/bucket.