[mrbonner]

It’s not a surprise for me to hear that Amazon is still a heavy user of RDBMS all these years even after the so-called Rolling Stone project to get rid of Oracle DB in 2015. If Amazon can use RDBMS for their scale, I’m just furious when folks jumping up and down screaming in top of their lungs “Why do we use Postgres and not (insert some random NoSQL engine here)?” My response so far is calmly ask another question “Why not?” And let them try to find a justification to suite our scale requirements.

[endisneigh]

It’s fascinating that this is your conclusion from the article. Mine would be that if you can make it work and believe these estimates then dynamodb is clearly more cost effective. And given that every project inevitably settles in access patterns and thus is a perfect fit for something like dynamodb, why bother with rdbms as the hot path? Just use dynamo and stream to a columnar database for analytics once your product is “finished”.

[bognition]

It all depends on your workload, access patterns, and data model.

You can absolutely spend an arm and a leg making a system work using a RDBMS that would be simpler and cheaper using a NoSQL store. The opposite is also true.

When picking a database you should always consider the trade offs of the different technologies and weigh those against your goals and budgets.

Sometimes is okay to spend more for a system that is just simpler to manage and use. Sometimes it’s not.

[orochimaaru]

Your application use cases should dictate the database choice - eg consistency needed, access patterns, data normalization, reliability, etc.