Telemetry: Database prefixes

[yorkshire-pudding]

Description of the need

Database prefixes have been part of Drupal for (?) years and were carried over into Backdrop. Most hosting that I've seen has no limit on numbers of databases, but the size of databases can sometimes be a problem, whether by limits from hosts or when exporting/importing. Exporting/importing individual sites from a database using prefixes requires more code.

If we added telemetry to measure the use of database prefixes, it could inform whether this "feature" could be removed/deprecated in Backdrop 2.0 any future features/development involving this area.

EDIT: @hosef said in Zulip:

Joseph Flatt: I don't think removing them is a good idea. Any change that removes functionality available in D7 is a huge mistake and makes it so that people who have more complicated sites will not consider using Backdrop.

Joseph Flatt: Also, Simpletest is totally dependent on database prefixes, so we would have to rebuild our testing infrastructure if we did that.

Proposed solution

We should track if sites are using database prefixes (Yes/No) as a Telemetry data-point.

[bugfolder]

I'm all for telemetry that informs future changes, but I will note that it's not uncommon for CiviCRM users to put the CiviCRM db into its own db, and then if you want to use modules that query both B and Civi dbs (e.g., CiviCRM Webforms), you need to (or at least, can) use prefixes. So removing/deprecating prefixes would break some sites that use a separate Civi db, including backdropcms.org.

[quicksketch]

It never hurts to have more data on our site configurations. I'd be in favor of collecting this simple boolean as well. You never know when you'll get a surprising number.