无法通过Putty连接R和PostgreSQL

Question

I have a problem with integration PostgreSQL and R. I always unload outputs from SQL queries into .txt file and then I download em into R using read.table() function. But now I need to get outputs from my queries directly in R. What I know about my SQL? It's PostgreSQL , I use PuttY to connect to db Also I know such information from PuttY about my connection as

1. Host name(or IP adress)
2. Port
3. saved session ='dbcenter'
4. ConnectionType = SSH
5. key -- its file with .ppk extension
6. passphrase for this key

Also, before writing queries, I choose in opened window

1. region
2. databases

This is full information i know about putty and i have no idea how to write queries directly in R script. I tried RPostgreSQL package, no success.

Can somebody help me?

Answer 1

Firstly, make sure you can connect to the remote DB without R, for example, using pgadmin3 or psql (see this link1 and link2 for more idea about pgadmin/psql/remote/port forwarding).

Then, try along these lines:

dbname <- "myname"; dbuser <- "myname"; dbpass <- "IWillNotTell";
dbhost <- "remotehostname"; dbport <- 5432;

If the remote host is withing the same local network (ie, your local host is myhost.host.edu), then, the following should work as well:

dbhost <- "remote"

library(RPostgreSQL)
drv <- dbDriver("PostgreSQL")
con <- dbConnect(drv, host=dbhost, port=dbport, dbname=dbname,
                 user=dbuser, password=dbpass)
query = 'SELECT * FROM TABLENAME'
dbGetQuery(con, query)
sqldata<-dbGetQuery(con, query)
summary(sqldata)

sqldata will be a dataframe

The important thing is firewall and access to the DB. I suggest, using pgadmin3 to make sure you can connect to the server.

If the local firewall does not allow connection to the postgresql server port then you'll need to use ssh tunneling - the connection can get pretty slow depending on how remote the remote host is. For example:

assuming the sever allows listens to only "localhost" (this is wrt to the server), then:

ssh -L 22222:localhost:5432 myname@remotehostname

will forward the 22222 port on your client to the remote's 5432 port. Again, use pgadmin3 at this point to make that you can connect.

Then set

dbhost <- "localhost"; dbport <- "22222"

and use the same dbConnect call. Once the dbConnect call is successfull all sql results will be in R local