When I first saw the option of create DBs, I thought it was something like I'm suggesting. MongoDB, MariaDB, CouchDB, etc, etc. This will be super cool. :)

t would be a good idea to have an SQL section where users can run optimization scripts like MYSQLTUNER etc and enter suggestioned changes in a GUI that directly change the mysql.conf directly and correctly.

An ability to monitor performance and tweak would be ideal, making the task of SQL performance monitoring and tweaking far easier.

Also optimize commands and other tasks could be run for this panel.

as well as optimize and the ability to add it to cron for weekly or monthly.

I'd be happy if you could integrate multiple MySQL Versions into Plesk. Each Customer should be able to choose his MySQL. Also choosing more than only one version should be implemented.

phpPgAdmin support was dropped starting from Plesk Onyx 17.8
This means that Plesk does not have any management tool for Postgres databases shipped with it.

I suggest to include pgadmin in Plesk installation since the latest ve
rsion of this software (2018-09-06 - pgAdmin 4 v3.3 Released) has just been released, with adequate security. More info about it you can find here:
https://www.pgadmin.org/

According to a ticket I just opened (80693) Plesk currently doesn't support a clustered MySQL server, e.g. an active/active Galera cluster.
To avoid data-loss or corruption in a server crash, I'd like to run MySQL in a Galera cluster to automatically sync the data again once Plesk's MySQL started after a crash.

The possibility to setup a replication for MySQL

Please do better integration of PostgreSQL into Plesk like CPU and memory usage in Health Monitoring and Dump button in Database page. Please also add PostgreSQL tuning into Plesk, especially for modern hardware with 32 or 64 GB memory and 4 to 8 cores and fast SSD or NVMe drives. Thanks!

Add the ability to create ODBC DNS for ODBC Driver 17 for SQL Server in Plesk.
Disabling TLS 1.0 breaks compatibility with earlier versions.

Plesk repair db should fix issue "Integrity constraint violation: 1062 Duplicate entry for key 'PRIMARY'"
https://support.plesk.com/hc/en-us/articles/115003292185-Unable-to-create-object-in-Plesk-SQLSTATE-23000-Integrity-constraint-violation-1062-Duplicate-entry-for-key-PRIMARY-

Many a times during database updates / ddl script executions the log file of MSSQL database becomes too large. There should be an option to shrink the log files. Currently this feature is disabled for both SQL Server Management Studio and Query.

Availability of reporting services on SQL server would be very useful on shared web hosting. My new ISP says Plesk doesn't support reporting services. I think it would be great if you did - not every site is a blog or simple brochure style. Any small scale business site still requires reporting, and SSRS is a natural fit for ASP.Net hosting.

Currently Plesk does not support MySQL Governor feature https://docs.cloudlinux.com/index.html?mysql_governor.html
and mapping file /etc/container/dbuser-map has to be updated manually

Plesk already has integration with CageFS and LVM and detects it once those features installed on the server. It would be great if support for MySQL Governor be implemented in future.

adding most common plugins (like network) to sw-collectd to send data to central collectd server->influxdb and process with grafana

They can be disabled by default (and optionally be enabled in PHP Settings, 7.0-7.1 only). The drivers appear to be quite stable - I have successfully installed them in Plesk on Ubuntu 16.04 and CentOS 7.4.

This is especially interesting since SQL Server 2017 is available for Linux and Docker.

Once the extensions are installed/enabled, the follow-up request would be to allow me to add remote MS SQL databases in Plesk Linux (not limited to RDS - any remote MS SQL instance).

Please add a simple button that retrieve my actual public IP and inserts it in the "Allow remote connections from" text area.
The page is the database user edit (or creation).

Implement the Contained Databases MS SQL feature in order to limit the database users ability to see MS SQL database names which are not owned by him.

Currently, when the database is copied the notification is sent to subscription owner.
It would be good to add functionality to disable such notifications or change the recipient mail address.

Within Plesk it is possible to create a dump of a (SQL Server) database. Plesk then seems to use 7Zip to create a .ZIP file. It would be nice if it was possible to choose between the .ZIP or the .7Z file format as .ZIP is more compatible, but 7Z compresses such database dumps up to 10 times better.
And of course you would need to be able to import 7Zipped dumps also.