Parameterised queries

Is there merit in using PostgreSQL?s arrays to send data from R to PostgreSQL? (Caveat: I say this having no idea how PL/R gets vectors from R to PostgreSQL.)

PL/R is able to pull vectors in from R, though RPostgreSQL cannot pulls arrays from PostgreSQL as vectors (though it would be great to have this feature).

The second and third approaches below do not differ in performance.

# Getting data one vector at a time

DROP FUNCTION IF EXISTS get_int_vector();

CREATE OR REPLACE FUNCTION get_int_vector()
  RETURNS integer[] AS
$BODY$
     sample(1:10)
$BODY$ LANGUAGE plr;

DROP FUNCTION IF EXISTS get_str_vector();

CREATE OR REPLACE FUNCTION get_str_vector()
  RETURNS text[] AS
$BODY$
     sample(letters[1:10])
$BODY$ LANGUAGE plr;

DROP FUNCTION IF EXISTS get_date_vector();

? For some reason, dates get converted to integers.
CREATE OR REPLACE FUNCTION get_date_vector()
  RETURNS date[] AS
$BODY$
     as.character(seq(from=as.Date("1971-01-01"), by=1, length.out = 10))
$BODY$ LANGUAGE plr;

WITH raw_data AS (
    SELECT get_int_vector() AS ints, 
        get_str_vector() AS strs,
        get_date_vector() AS dates)
SELECT 
    UNNEST(ints) AS int,
    UNNEST(strs) AS str,
    UNNEST(dates) AS date
FROM raw_data;

## Via RPostgreSQL

system.time({
    n <- 1e6
    df <- data.frame(int=sample(1:10, size=n, replace=TRUE),
                     str=sample(letters[1:10], size=n, replace=TRUE),
                     date=as.character(sample(seq(from=as.Date("1971-01-01"), 
                                                  by=1, length.out = 10), 
                                              size=n, replace=TRUE)),
                     stringsAsFactors=FALSE)

    library("RPostgreSQL")

    pg <- dbConnect(PostgreSQL())

    dbWriteTable(pg, "rpostgresql_test", df, row.names=FALSE, overwrite=TRUE)
})

## Using composite type created with table

DROP TABLE IF EXISTS plr_test CASCADE;

CREATE TABLE plr_test (int integer, str text, date date);

CREATE OR REPLACE FUNCTION get_df()
  RETURNS SETOF plr_test AS
$BODY$
    n <- 1e6
    df <- data.frame(int=sample(1:10, size=n, replace=TRUE),
                    str=sample(letters[1:10], size=n, replace=TRUE),
                    date=as.character(sample(seq(from=as.Date("1971-01-01"), 
                                                by=1, length.out = 10), 
                                             size=n, replace=TRUE)),
                    stringsAsFactors=FALSE)
    return(df)
$BODY$ LANGUAGE plr;

INSERT INTO plr_test
SELECT * FROM get_df();