[docs] Create documentation for DB Server specific requirements

[scara]

What is the Moodle feature that needs documenting?

Sometimes - e.g. MDL-70260, MDL-76572 - we need more details about what patch level is actually required for a DB Server in order to let Moodle work fine using its features.

In the past we were used to quote Tracker issues in the "See also" section but for this specific argument we should find a place to collect such information.

In detail, we need to highlight that using Microsoft SQL Server 2019 will require at least Cumulative Update Package 18 for SQL Server 2019 - KB5017593 to let Moodle Backup&Restore processes to properly work.
Note: since MS SQL is mostly Community supported we are not sure that a lower CU could work either.

HTH,
Matteo

Is this documentation specific to a Moodle version?

No

Are you able to provide a patch for this?

None

[scara]

Adding other related references to the Moodle Tracker:

• MDLSITE-6045, the sensitive one for testing purposes too
• MDL-72550
• MDL-77118 : About to add a custom env check.

HTH,
Matteo

Edited: To add link to custom env check issue.

[stronk7]

Note that, as part of MDLSITE-6045 (thanks @scara for all the testing there!) it has been detected that:

• 2017 runs ok (any CU).
• 2019 requires, at very least, CU1.

So we should add that information somewhere (say release notes, server requirements, saying something like "if using SQL*Server 2019, cumulative update 1 (CU 1) is required" and "it's always recommended to run the latest CU available". Just suggesting.

Candidate places I can imagine:

• https://moodledev.io/general/releases/4.1#database-requirements
• https://docs.moodle.org/401/en/MSSQL
• Not sure about this: https://docs.moodle.org/401/en/Using_the_Microsoft_SQL_Server_Driver_for_PHP