[fubbyy]

I think it also depends on the system you’re using it on. I think one of the biggest advantages of DDB is that is scales so well (with good design to avoid hot partitions). Afaik, RDBMS simply cannot scale in the same way due to their design. Yes, they can scale somewhat, but as you said it requires lots of tuning, and you’ll still reach a hardish limit.

[grogers]

One partition of DDB is incredibly tiny compared to one partition of an RDBMS. You can push that one partition of RDBMS pretty far before you're forced to design sharding into your system. With DDB you are basically forced to design sharding into your partition keys up front or you will have hot partition issues. This is by far the most common problem I see with teams using DDB, so brushing it off as "with good design to avoid hot partitions" is understating the scope of the problem.

[manigandham]

All databases scale the same way - by partitioning and sharding the dataspace. RDBMS have harder restrictions due to the features they provide and the performance expectations, but you can just as easily use a bunch of relational servers to partition a table (or several) across them by range or hashes of the primary key.

That's basically what key/value stores like DynamoDB do, and why DynamoDB was even built on MySQL (at least originally).

[dalyons]

"can just as easily use a bunch of relational servers to partition a table" is not true at all. Managing, maintaining and tuning a sharded relational cluster is an astonishing amount of operations work. partition management, re-partioning, partition failover / promotions / demotions, query routing, shard discovery, upgrades... it goes on an on. All this work is gone if you pick dynamo. Not saying that dynamo is always better, but IMHO people very much underestimate the ops cost of running a sharded relational cluster at scale.

[manigandham]

The point is the scaling fundamentals are the same across databases.

Whether that work is managed or not is a different topic, and you can find plenty of managed offerings of scale-out relational databases.

[kixiQu]

"just as easily" would be the contested part, I'd guess