options(java.parameters = "-Xmx8048m")
psql.jdbc.driver <- "../postgresql-42.2.1.jar"
jdbc.url <- "jdbc:postgresql://server_url:port"
pgsql <- JDBC("org.postgresql.Driver", psql.jdbc.driver, "`")
con <- dbConnect(pgsql, jdbc.url, user="", password= '')
tbl <- dbGetQuery(con, "SELECT * FROM my_table;")

Error in .verify.JDBC.result(r, "Unable to retrieve JDBC result set for ",  :
Unable to retrieve JDBC result set for SELECT * FROM my_table; (Ran out of memory retrieving query results.)