Redis is one of the most beloved data stores according to StackOverflow survey. Amazon Web Services offers managed Redis as ElastiCache. It has many features that allow us to build great systems; one of them is replication. How does it work?

What is Redis and AWS ElastiCache

Redis is a cache. It is a fast in-memory NoSQL data store. Unlike databases, Redis does not store its data on disk. Instead, it keeps the whole dataset in memory. This allows Redis to offer performance that is far superior to traditional databases. Using Redis in your system can decrease latency, make the system simple, and reduce operating cost…

Wishing you had one extra hour every day to get more done? Probalby yes. Would you be even more productive if you had 30 hours a day? It seems so, but, actually, I am pretty sure that the answer is negative.

The most intuitive idea is that if you had more time you would get more things done. We tend to believe the intuition that if we had twice as much time, we would be able to produce twice as much output. If humans were machines, that would pretty much be the case. But humans are not. We don’t scale…

How do we know when to stop writing unit tests? When we run out of ideas for tests? When we test all possible scenarios? When the clock hits 5 o’clock? How do we know that we have written enough tests? One commonly used measure is code coverage.

What is a code coverage? It is usually a number that tells you how much of your code is “covered” by tests. To calculate that number, testing frameworks just count number of lines of code that were executed while running a suite of tests. Then they just give a number, for example, 60%.

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