The document discusses key considerations for database selection, including data type and volume, scale, traffic patterns, consistency requirements, and other factors. It notes that incorrect database selection can lead to performance issues, application failures, high costs, and outages. The CAP theorem is also summarized, which states that a distributed database can only prioritize two of three properties: consistency, availability, and partition tolerance. CP databases prioritize consistency and partition tolerance over availability, while AP databases prioritize availability and partition tolerance over consistency.

1. Database selection
Rajeev Rathor
[B.Tech, M.Tech]
Architect @ Reliance JIO
Ex of Samsung, OLA, FICO, CSC

2. What Happen If Database Selection is Incorrect
 Performance Issue
 Application May Fail to deliver Quality Services
 High Cost of Services
 High Cost of Migration
 Scaling issue
 Outage

3. Key Aspect for Database Selection
 Data model
 Type Of Data [ Structured, Semi Structured, Unstructured]
 Volume and Velocity & Variety
 Scale [Vertical and Horizontal]
 Traffic [ Volume of Data ingest per second and Predictability of
traffic ]
 Consistency Level [Absolute Consistency or Eventual ]
 Read OR Write Intensive
 Type Of Operation [Join, Filter, Projects]
 Availability

4.  Sharding [Partitioning]
 Analytics [Analytics with low latency, Aggregations]
 Durability [ In-Memory, or Durability]
 Integration [With Various frameworks or lib, visualization]
 Reporting and Visualization
 Data Security
 Data Protection and Compression
 Fail-over Mechanism [recovery and Downtime]
 License and Procurement Cost

5. CAP Theorem
https://www.ibm.com/cloud/learn/cap-theorem

6.  Consistency
Consistency means that all clients see the same data at the same
time, no matter which node they connect to. For this to happen,
whenever data is written to one node, it must be instantly
forwarded or replicated to all the other nodes in the system
before the write is deemed ‘successful.’
 Availability
Availability means that that any client making a request for data
gets a response, even if one or more nodes are down. Another
way to state this—all working nodes in the distributed system

7.  CP database:
A CP database delivers consistency and partition tolerance at the
expense of availability. When a partition occurs between any
two nodes, the system has to shut down the non-consistent
node (i.e., make it unavailable) until the partition is resolved.
Example: MongoDB, DynamoDB, Hbase, Redis
 AP database:
An AP database delivers availability and partition tolerance at the
expense of consistency. When a partition occurs, all nodes
remain available but those at the wrong end of a partition might
return an older version of data than others. (When the partition

8. Thanks