This post explains what Data Replication is and how it differentiates from ETL/ ELT, what Change Data Capture (CDC) is, and a few Qlik Replicate use cases.
Category: NoSQL Databases
A NoSQL database (initially referred to as “non-SQL” or “non-relational”) provides a mechanism for storage and retrieval of data which is an alternative to the tabular relations used in relational databases.
These databases have existed for a long time. Their popularity increased in the latest years, where different database technologies have been developed in response to the demands of building applications such as Web 2.0, analytics, IoT, etc.
The NoSQL databases don’t replace the relational ones. They are not ACID (Atomicity, Consistency, Isolation, Durability) databases either. Thus, a NoSQL database will not be adequate if you have a transactional workload where normalisation and consistency are the primary requirements.
Some reasons to use NoSQL databases are:
- Reduce unneeded complexity,
- High throughput to ingest and retrieve data,
- Avoid mapping between related objects, as the use of simpler objects,
- Trade reliability for better performance,
- Lower overhead and memory footprint than relational databases,
- Cope for use cases that don’t fit in a relational database, a file system or a data lake,
- Adapt to the cloud, and
- Optional ways to access data.
The NoSQL data stores are a heterogeneous group of databases. Generally speaking, they are classified into the following groups: Column, Document, Key-value and Graph. Even though, on some occasions, the classification is more detailed. In any case, the distinction between NoSQL data stores types is not so clear. One database may be based on a key-value architecture but implement some document features or a graph NoSQL store.
You will find posts on NoSQL databases in this category.
Migration from PostgreSQL to MongoDB on AWS
This post explains how to differentiate among the different types of NoSQL databases. and how to plan a migration from PostgreSQL to MongoDB.
Planning a Database Migration
The secret sauce of a successful migration is planning and architecture. In this post we discuss the different aspects you must consider.