[partoa]

1. Depends. If you have a lot of update queries, MySQL wins [https://eng.uber.com/mysql-migration/]. MySQL also has better replication and sharding support at the moment.

2. PostgreSQL and MYSQL also sport JSON... JSON functions can be a little tricky. Still, they work.

3. Depends on the structure of your XML. Might even possible to use RegEx to achieve this objective. XML to JSON is easier though. That can be saved in JSON fields in a DB.

4. You can build a custom file based on anything. The only catch, the SQLite client will only read a valid SQLite file. As such, you have to know what you're doing.

[Edit] Formating

[jiggawatts]

That's incredibly well written, constructive feedback by the Uber team! I wonder if the Postgres team has taken this on board and attempted to resolve some of the design issues, e.g.: by moving the cache in-process.

[jeltz]

The Uber team betrays their lack of knowledge about PostgreSQL in the article, so take it with a huge grain of salt. I recommend reading Markus Winand's article.

https://use-the-index-luke.com/blog/2016-07-29/on-ubers-choi...

But that does not mean though that there are not also real issues with table bloat in PostgreSQL, and they are being worked on by creating a new storage engine with a different MVCC implementation.