Test if database is online

[dpriddle1331311432]

This question has probably already been answered somewhere, but I'm having trouble finding the answer.

I want to be able to test if a given database server is online.

Using databaseManager.getServerNames() I'm able to generate a list of all the databases that were enabled at startup. But how, without doing some kind of actual query on the database, can I determine if the database is online?

Or perhaps I should ask is there an inexpensive querry I could perform that would tell me if a given database is online?

Ideally, this should work for both traditional databases such as mysql and postgresql as well as others such as MongoDB and FileMaker.

[jdbruijn]

My guess would be to use the maintenance plugin (see isValid() for JSServer), I never used this but it seems to me a check for an active server. Or you could run a simple query on the server (i.e. select 1 from table).
The last option would recieve a time-out if the server is offline, so you would have to wait until that time-out expires and I think that is depending on the db settings.