[R-sig-Geo] install rgdal to query postgis database

[Duncan McPherson]

Thanks for your suggestion.

The user postgres has a password already (see below for detail). I tried as you suggested:

> dsn="PG:dbname=england_health user=postgres password=[password]"
> ogrListLayers(dsn)
Error in ogrListLayers(dsn) : Cannot open data source

and all the variations as before. I also created a new postgres user 'duncan', with the same password as my system login password and used this in case there was some conflict between the logged in user and the database role. That didn't help either, although I can make all the other connections as either postgres or duncan (including DBI+RPostgreSQL).

Your suggestion got me to digging around in my postgresql configuration. It turns out that my pg_hba.conf file has

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local	 all		all					trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     postgres                                trust
#host    replication     postgres        127.0.0.1/32            trust
#host    replication     postgres        ::1/128                 trust

which means, to my reading, that any user should be trusted to connect from localhost (I may have to look into this more, since there are suggestions this isn't secure, but that is another story). So, even if a user has a password set, it shouldn't be checked.

I am curious also as to why DBI/RPostgreSQL can connect and get data from the database freely, but Rgdal cannot? They must be doing something different that I can't figure out?