How to connect to Postgres using DBI in R? - r

Question

Trying to connect to Postgres using DBI for first time to use dbplyr.
Issue: I am trying to use dbplyr with my exiting odbc connection but dbplyr doesn't seems to work with that so trying to create a new connection using DBI but this dbi connection is giving an error. So I am looking to fix dbi connection.
When I try to replicate my existing connection using DBI then connection doesn't work:
libs
library(odbc)
library(RODBC)
library(DBI)
library(dplyr)
library(dbplyr)
# from: https://stackoverflow.com/questions/59413904/reading-data-from-a-sql-server-in-rstudio-dplyr
# from: /help/library/DBI/html/dbConnect.html
# from: https://github.com/r-dbi/odbc#odbc
dbicon <- DBI::dbConnect(
odbc::odbc(),
driver = "PostgreSQL Unicode",
database = "Postgres_xyz_db",
host = "some_xyz.amazonaws.com",
port = "5432",
uid = "user",
pwd = "users_password")
# connect with table
tbl_qry <- tbl(dbicon, "mydb_demo.demo_table")
tbl_qry %>% head()
Error with dbConnect step:
Error: nanodbc/nanodbc.cpp:1021: 00000: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
In addition: Warning message:
In for (i in seq_len(n)) { : closing unused RODBC handle 2
PS:
I am running this on localhost:8787
My Existing odbc / RODBC connection which is working for the same db.
libs
library(odbc)
library(RODBC)
library(dplyr)
library(dbplyr)
Existing Working connection:
## #################################################################
## Connection Para
## #################################################################
driver.name <- "PostgreSQL Unicode"
db.name <- "Postgres_xyz_db"
host.name <- "some_xyz.amazonaws.com"
port <-"5432"
user.name <-"user"
pwd <- "users_password"
## #################################################################
## connect to a database
## #################################################################
con.text <- paste("DRIVER=",driver.name,
";Database=",db.name,
";Server=",host.name,
";Port=",port,
";PROTOCOL=TCPIP",
";UID=", user.name,
";PWD=",pwd,sep="")
con1 <- odbcDriverConnect(con.text)
But dbplyr doesn't work with this connection
# connect with table
tbl_qry <- tbl(con1, "mydb_demo.demo_table")
tbl_qry %>% head()
(I am not really a techy or db admin or devops guy so pls excuse if it looks kind of filled with basic mistakes).

Answer 1

odbc connections prefer server= over host=, so your connection attempt should likely be
dbicon <- DBI::dbConnect(
odbc::odbc(),
driver = "PostgreSQL Unicode",
database = "Postgres_xyz_db",
server = "some_xyz.amazonaws.com",
port = "5432",
uid = "user",
pwd = "users_password")