Key Value Stores
They are a very single database but they are really fast
It stores data as a key and a value which can be a large list of serialized data
Ideal data store when we want to fetch values based on a single property and don’t want to query based on other properties
They lack Relations, Indexes and Aggregation features
They are stored as dictionaries (aka Associative Arrays/ Hash’s)
They can represent tabular data as well, but the column in each row does not have to be consistent
Due to their simple design they are easy to scale
Document Stores
A NoSQL database that stores documents as its primary data structure
The document could be XML data but they are mostly JSON or JSON like data (BSON)
They are a subclass of Key Value store
We can create secondary keys to speedup performance
Suitable for applications where data needs to fetched based on a column that is more complex that document key
Tables - Collection
Rows - Documents
Columns - Fields
Joins - Embedding and Linking
Columnar Database
Key value data store that structure data storage into collections of related columns
We can read that from a single column family without having to access all the columns
Graph Database
A data structure that uses vertices (nodes) which form relationship to other vertices via edges (lines)
A node will contain data properties. The edges relationship data such as direction and data properties
Ideal for cases for relation between entities need to be mapped
Use cases:
- Fraud Detection
- Network and IT Operations
- Identity and Access Management (IAM)
- Contact Tracing
- Social Media Graphing
Telemetry and Time Series
It is an append only collection of objects
They store attributes allow with time/ timestamp/ time span in which it occurred
They store data in an efficient manner using column stores and in-memory structures
Temporal Elements
- Valid Time: A time range in the real world in which the value is valid
- Transaction Time: The time at which the data was added into the database
- Decision Time: The time at which decision related to the data was made