I don't want to defame the author, but I must ask: are they in any way affiliated with Amazon, do they resell Amazon services?

I ask because there are things that would appear to be errors on the comparison matrix, and Amazon Aurora is listed as receiving full marks in every category, as if it was the greatest of all the solutions!

Some issues I see:

Amazon Aurora has checkboxes for horizontally scalable (none) and automatic data sharding (none), and for latency, this is simply assumed. But Aurora is backed by disks (or provisioned IO SSDs) and it's not at all comparable to memcached in terms of latency. (See: >5ms writes in [1], which places Amazon Aurora about what I'd expect any SQL database to be at, 1-10ms for read and writes.)

CosmosDB has no checkbox for ACID or Automatic Data Sharding. "All JavaScript logic is executed within an ambient ACID transaction with snapshot isolation. During the course of its execution, if the JavaScript throws an exception, then the entire transaction is aborted." [2], and "Partition management is fully managed by Azure Cosmos DB, and you do not have to write complex code or manage your partitions. Cosmos DB containers are unlimited in terms of storage and throughput." [3]. The "partition key" might be something of a misnomer. For a multi-tenant service, the partition key can be used to limit the performance of a tenant by assigning them one partition key, but if there is no desire to restrict performance, the partition key can be a randomly generated identifier.

MongoDB has no checkbox for automatic data sharding, but practically speaking the hash-based sharding is fine. It's really curious that the author gives Aurora a checkbox here, but not MongoDB. Is it not normal for `distributed` tables to be used in MongoDB deployments? I would guess it is.

Lastly, I just don't think Aurora is the same type of database as Google's Cloud Spanner and Microsoft's Cosmos DB. The latter are, really, a new kind of database, and Aurora is a managed MySQL or Postgres instance.

[1] https://pagely.com/blog/2015/08/we-benchmarked-amazons-new-a...

[2] https://docs.microsoft.com/en-us/azure/documentdb/documentdb...

[3] https://docs.microsoft.com/en-us/azure/cosmos-db/partition-d...