[R-sig-DB] RFI on changing behavior in next RMySQL release

[Jeffrey Horner]

Hi,

A situation has been brought to my attention by two RMySQL users who have
posted their issues on github.

As followers of this mailing list, most will be familiar with the two ways
in which SQL queries are executed and results obtained via the DBI:

1. users execute dbSendQuery(), get back a result set object and use
subsequent functions dbHasCompleted(), fetch(), and possibly
dbClearResult() act on the result set.

2. users execute dbGetQuery() to perform just one function to execute the
SQL, gather the result set, and return to the user.

In RMySQL, connection level options can be set that affect the work done
for the duration of the connection only. For instance, one user sets the
connection level character set to ensure that all results are transferred
in UTF8.

The issue is that RMySQL will create temporary connections unbeknownst to
the user during a call to dbGetQuery() if the user has previously performed
a dbSendQuery() without getting rid of the returned result set object. In
essence, this is a user who has not been enlightened on exactly what's
going on, they didn't fully read and comprehend the documentation.

I'd like to get rid of the temporary connection feature, let's call it
cloning the connection as that's the name of the low level mysql C function
that takes care of creating the temporary connection, but I'd like to make
this change in a way that doesn't place too much stress on the user.

So, here are some options I've come up with to alter dbGetQuery() and the
other functions that create temporary connections, but I'd like to get the
list users opinions on this before I release:

A) Do I silently remove the pending result set objects altogether,
B) Do I do A but with a warning,
C) Do I throw an error and let the user fix his/her code,
D) Do I add a dbConnect() connection argument called 'clone' that tells
whether or not to allow temporary cloning of the connection, and what
should the default argument value be, TRUE or FALSE?

D) was suggested by a github user, so I'm inclined to go with that.

Thanks for your thoughts on this.

Jeff

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