Re: BUG #5304: psql using conninfo fails in connecting to the server

Joe Conway <mail@joeconway.com> writes:
> On 02/02/2010 06:10 PM, Tom Lane wrote:
>> We should also give more than zero thought to how values coming from the
>> expanded dbname should interact with values from other arguments to
>> PQconnectdbParams --- which should override which?  And should there be
>> an order dependency?

> My first thought was to duplicate the logic used by PQsetdbLogin(). It
> uses the conninfo string, fills in the defaults using connectOptions1(),
> applies the supplied other arguments overriding the defaults, and then
> finally computes derived options with connectOptions2(). It is
> essentially the same as PQconnectdb() except the supplied parameters are
> used before setting the derived options.

The difference with PQconnectdbParams is that the dbname might not be
the first thing in the parameter array.  I think that a straightforward
implementation would have the effect of the expanded dbname overriding
parameters given before it, but not those given after it.  Consider

    keyword[0] = "port";
    values[0] = "5678";
    keyword[1] = "dbname";
    values[1] = "dbname = db user = foo port = 9999";
    keyword[2] = "user";
    values[2] = "uu";

What I'm imagining is that this would end up equivalent to
dbname = db user = uu port = 9999.  That's probably reasonable,
and maybe even useful, as long as it's documented.

            regards, tom lane