UTF-8 / Unicode Text Encoding with RPostgreSQL

Question

I'm running R on a Windows machine which is directly linked to a PostgreSQL database. I'm not using RODBC. My database is encoded in UTF-8 as confirmed by the following R command:

dbGetQuery(con, "SHOW CLIENT_ENCODING")
#   client_encoding
# 1            UTF8

However, when some text is read into R, it displays as strange text in R.

For example, the following text is shown in my PostgreSQL database: "Stéphane"

After exporting to R it's shown as: "Stéphane" (the é is encoded as é)

When importing to R I use the dbConnect command to establish a connection and the dbGetQuery command to query data using SQL. I do not specify any text encoding anywhere when connecting to the database or when running a query.

I've searched online and can't find a direct resolution to my issue. I found this link, but their issue is with RODBC, which I'm not using.

This link is helpful in identifying the symbols, but I don't just want to do a find & replace in R... way too much data.

I did try running the following commands below and I arrived at a warning.

Sys.setlocale("LC_ALL", "en_US.UTF-8")
# [1] ""
# Warning message:
# In Sys.setlocale("LC_ALL", "en_US.UTF-8") :
#   OS reports request to set locale to "en_US.UTF-8" cannot be honored
Sys.setenv(LANG="en_US.UTF-8")
Sys.setenv(LC_CTYPE="UTF-8")

The warning occurs on the Sys.setlocale("LC_ALL", "en_US.UTF-8") command. My intuition is that this is a Windows specific issue and doesn't occur with Mac/Linux/Unix.

Answer 1

As Craig Ringer said, setting client_encoding to windows-1252 is probably not the best thing to do. Indeed, if the data you're retrieving contains a single exotic character, you're in trouble:

Error in postgresqlExecStatement(conn, statement, ...) : RS-DBI driver: (could not Retrieve the result : ERROR: character 0xcca7 of encoding "UTF8" has no equivalent in "WIN1252" )

On the other hand, getting your R environment to use Unicode could be impossible (I have the same problem as you with Sys.setlocale... Same in this question too.).

A workaround is to manually declare UTF-8 encoding on all your data, using a function like this one:

set_utf8 <- function(x) {
  # Declare UTF-8 encoding on all character columns:
  chr <- sapply(x, is.character)
  x[, chr] <- lapply(x[, chr, drop = FALSE], `Encoding<-`, "UTF-8")
  # Same on column names:
  Encoding(names(x)) <- "UTF-8"
  x
}

And you have to use this function in all your queries:

set_utf8(dbGetQuery(con, "SELECT myvar FROM mytable"))

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EDIT: Another possibility is to use RPostgres unstead of RPostgreSQL. I tested it (with the same config as in your question), and as far as I can see all declared encodings are automatically set to UTF-8.