OK. That explains why scripts that worked on my XP system no longer work on my Vista system. The former had DBD::Pg and the latter DBD::PgPP

The problem is implementation differences between DBD::Pg and DBD::PgPP. The former defaults to making a tcp connection unless you set the host parameter to path, in which case it will try for a unix-domain socket. On Win, it could try for a named-pipe connection. I guess it would just take for someone to write the patch.

(I wonder why the PgPP author deviated and introduced the path parameter. It makes the host default useless.)

Looking at the source, it looks as though there technically is no default hostname. Check out the _connect sub, and you'll see that it checks whether hostname is defined to decide whether to try a TCP socket. But looking a few lines up at new, there isn't any default for hostname, it has to be passed as an argument to new():

sub new {
    my ($class, %args) = @_;

    my $self = bless {
        hostname              => $args{hostname},
        path                  => $args{path}     || DEFAULT_UNIX_SOCKE
+T,
        port                  => $args{port}     || DEFAULT_PORT_NUMBE
+R,
#...snip!
[download]

Yeah, The POD is out of step with the code (and the default behaviour is different from DBD::Pg).

      parameter | hard coded default
      ----------+-------------------
      dbname    | current userid
      host      | localhost
      port      | 5432
      path      | /tmp
      debug     | undef
[download]

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

The former defaults to making a tcp connection unless you set the host parameter to path,

Are you sure? The documentation for DBD::Pg says it defaults to using a local domain socket when the host isn't specified (which is what DBD::PgPP does).

Are you sure?

Yes. Quite sure. This script (just userid & password obscured):

#! perl -sw
use 5.010;
use strict;
use threads;
use DBI;

my $dbh = DBI->connect("dbi:Pg:dbname=junk", '******', '********');
say $dbh;

my $sth = $dbh->prepare( 'Select * from fred' );
$sth->execute;
while( my @row = $sth->fetchrow_array ) {
    say "@row";
}
[download]

Produces this output:

c:\test>DB.pl
DBI::db=HASH(0x40ae870)
1 fred
2 bill
3 jack
4 joe
[download]

So, maybe PgPP followed Pg's POD and not it's behaviour?

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."