AWS dynamo DB training : Basics

 Each dynamo DB table is a collection of items and each item consists of a group of attributes. One or two attributes are used as primary keys. One attribute is used by dynamo DB for partitioning. We could also define a second attribute as sort key which the dynamo DB uses to sort each partition. 

Single table per application

Items are similar to rows in a relational DB. There is not limit to the number of items in a table. 

Attributes are similar to columns in a relational database. Attributes can be scalar or nested. 

When you create a table you must specify a primary key. Primary key can only be a scalar. You can also define an attribute as a sort key and one attribute as a partition key. 

Primary key is used as partition key. Items are stored and retrieved using this partition key.

Two types of access patterns for table- queries and scans. Queries are based on primary key and read selected items. Scan on the other hand read all the items. 

Local secondary index can only be added at the time of table creation. YOu can create upto 5 LSI

A global secondary index can be created any time. You can add upto 25 GSI