Database Reference
In-Depth Information
Data model concepts
To understand DynamoDB better, we need to understand its data model first. DynamoDB's
data model includes
Tables
,
Items
, and
Attributes
. A table in DynamoDB is nothing but
what we have in relational databases. DynamoDB tables need not have fixed schema (num-
ber of columns, column names, their data types, column order, and column size). It needs
only the fixed primary key, its data type, and a secondary index if needed, and the remain-
ing attributes can be decided at runtime. Items in DynamoDB are individual records of the
table. We can have any number of attributes in an item.
DynamoDB stores the item attributes as key-value pairs. Item size is calculated by adding
the length of attribute names and their values.
Tip
DynamoDB has an item-size limit of 64 KB; so, while designing your data model, you
have to keep this thing in mind that your item size must not cross this limitation. There are
various ways of avoiding the over spill, and we will discuss such best practices in
Chapter
The following diagram shows the data model hierarchy of DynamoDB:
