Deprecate dbListResults()

[krlmlr]

Seems to be unsupported by existing backends, sometimes only one active result set is supported. Deprecate?

[hadley]

Yes, should be deprecated.

[bborgesr]

How to go about closing all open result sets if dbListResults is deprecated? This is important for pool when passivating a connection:

setMethod("onPassivate", "DBIConnection", function(object) {
  rs <- dbListResults(object)
  lapply(rs, function(x) {
    if (dbIsValid(x)) {
      dbClearResult(x)
      dbRollback(object)
    }
  })
})

[hadley]

You need to maintain your own list if that's important - there's no guarantee that that code would work correctly today.

[bborgesr]

@jcheng5 -- should we change this now? Or are we happy with using this method for the first release? It seems to work fine for RSQLite and MySQL, at least.

[jcheng5]

@hadley It's hard for us to maintain a list because we hand out connections with poolCheckout(), we're not privy to what happens to the connection after that.

What specifically about Barbara's code won't work correctly today? We know there's the problem with SQLite but dbIsValid seems to work around that. Will there be resultsets that are active but not returned?

[hadley]

@jcheng5 I don't think in general you should assume that dbListResults() is reliable - I don't remember the details, but I'm reasonably certain at least one of the big 3 has problems.

[bborgesr]

Just for future reference: the deprecation of dbListResults() will no longer be an issue for pool after DBI implements a dbResetConnection() generic (see #117).