I recall this coming up before, but I can't find it in the list of open or closed postgres bugs.

It appears as though PHP is using the arguments to pg_connect to uniquely identify connections. For example:

 $dba = pg_connect("user=foo pass=bar dbname=baz");
 $dbb = pg_connect("user=foo pass=bar dbname=baz");
 pg_close($dba);
 # $dbb is closed now too

Were one to use $dbb at this point, one would see

PHP Warning:  1 is not a valid PostgreSQL link resource in [file] at [line].

But,

 $dba = pg_connect("user=foo pass=bar dbname=baz");
 $dbb = pg_connect("pass=bar user=foo dbname=baz");
 pg_close($dba);
 # $dbb is still open

and

 $dba = pg_connect("user=foo pass=bar dbname=baz");
 $dbb = pg_connect("user=foo pass=bar dbname=baz    ");
 pg_close($dba);
 # $dbb is still open

The bug doesn't require that the handle be closed explicitly; I discovered it here where one of our programmers was having connections close when one fell out of scope.

I tried moving back to PHP 4.0.2 but the bug's there too (so it doesn't look to be a regression problem); on the other hand, a DEC Alpha running Digital Unix 4.0e and PHP 4.0.2 does *not* exhibit this behaviour.

If you're unable to duplicate it, please get in touch with me, and I'll see if I can make arrangements for a testing environment. I'll poke through the code myself for something obvious, but I'm unfamiliar with PHP internals in the first place (up to now, at least).