PostgreSQL as a Service

Hello everyone!

tl;dr: How well is PostgreSQL positioned to serve as the database of choice 
for a DBaaS operator? Specifically, how much open source is (may be) missing?

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Im un-lurking hoping to learn more about PostgreSQL in DBaaS land.

You may have seen this announcement.

https://blog.yugabyte.com/why-we-changed-yugabyte-db-licensing-to-100-open-source/

YugaByte bills itself as a PostgreSQL compatible database (yay to at least the 
intent) but most importantly, it decided to single-license its database under 
a permissive license, including "the enterprise features" that frequently are 
held back by single-vendor open source firms who want to earn a RoI for their 
VC investment.

The interesting part (and why I'm posting it here) is the following staging of 
functionality implied in that post.

1. Core database (permissively licensed)
2. Enterprise features (permissively licensed)
3. DBaaS features (trial license, commercial, no open source)
4. Managed by YugaByte (commercial)

Point 3. suggests that they want to make money from self-managed DBaaS, but in 
the post they also write they really only expect significant income from 4, 
i.e. YugaByte (the database) managed by YugaByte (the company).

Where is PostgreSQL in relation to this?

1. PostgreSQL itself is certainly 1 above, the core database.

2. PostgreSQL permissive license allows commercial offerings to build and not 
share enterprise features (and I'm sure some companies are holding back). 
However, PostgreSQL is true community open source so whatever enterprise 
features become relevant, they'll eventually be commoditized and out in the 
open. Is there a lot that is missing? And that some companies have but are not 
contributing?

3. So, PostgreSQL as-a-service. There are several companies (plenty?) who 
service PostgreSQL. I wonder how this is being shared back? I don't have a 
clear picture here, my impression is that the software to run these 
potentially large farms is proprietary? Or, that operators would argue, this 
is all configuration and shell scripts and not really shareable open source?

One aspect related to as-a-service is scaling out, i.e. not just having many 
small customers, but also serving large customers in the cloud. I looked 
around for scaling out solutions. There used to be CitusData (not any longer 
it seems), there is PostgresXL which seems to be moving slowly. Is that it?

4. Managed DBaaS is not relevant here but always a commercial offering.

So, back to my main question above. If I wanted to run a DBaaS shop with only 
PostgreSQL open source, how far away from being able to compete with AWS or 
Azure (or YugaByte for that matter) would I be?

Thanks for any thoughts and opinions! Dirk

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