> With each trip generating multiple ledger entries, and Uber as a whole processing 15 million trips per day, it didn’t matter that DynamoDB was great because of high throughput at global scale. The proverbial bean counter should’ve stopped this madness from happening.

> At Uber’s scale, DynamoDB became expensive. Hence, we started keeping only 12 weeks of data (i.e., hot data) in DynamoDB and started using Uber’s blobstore, TerraBlob, for older data (i.e., cold data). TerraBlob is similar to AWS S3. For a long-term solution, we wanted to use LSG.

Honest question. Why do people go for this kind of complicated solution? Wouldn't Postgres work? Let's say each trip creates 10 ledger entries. Let's say those are 10 transactions. So 150 million transactions in a day. That's like 2000 TPS. Postgres can handle that, can't it?

If regional replication or global availability is the problem, I've to ask. Why does it matter? For something so critical like ledger, does it hurt to make the user wait a few 100 milliseconds if that means you can have a simple and robust ledger service?

I honestly want to know what others think about this.

I have been a part of over-built solutions.

It’s usually because executive management bakes hyper growth into the assumptions because they really want the biz to grow, then it becomes marching orders down the chain as it gets misinterpreted in a game of corporate telephone.

“We need to design this for 1b DAUs”

Then 1) that growth never happens and 2) you end up with a super complicated solution

Instead, someone needs to say, “Hey [boss], are you sure we need to build for 1b DAUs? Why don’t we build for 50m first, then make sure it’s extensible enough to keep improving with growth”

SRE here. Most of time we see choices like this because teams are under pressure to deliver and scale would likely exceed what a database will easily handle with the out of the box settings. So tweaking is required and that takes time/knowledge that Dev team doesn't have. AI helps a bit here but it didn't exist when DynamoDB solution was chosen. However, some terraform, and boom, scalable database created, only downside is the cost which is next Product Manager problem.