RPostgres (version 1.0-3)

postgres-tables: Convenience functions for reading/writing DBMS tables

Description

Convenience functions for reading/writing DBMS tables

Usage

# S4 method for PqConnection,character,data.frame
dbWriteTable(conn, name, value,
  ..., row.names = FALSE, overwrite = FALSE, append = FALSE,
  field.types = NULL, temporary = FALSE, copy = TRUE)
# S4 method for PqConnection
sqlData(con, value, row.names = FALSE, copy = TRUE)
# S4 method for PqConnection,character
dbReadTable(conn, name, ...,
  check.names = TRUE, row.names = FALSE)
# S4 method for PqConnection
dbListTables(conn, ...)
# S4 method for PqConnection,character
dbExistsTable(conn, name, ...)
# S4 method for PqConnection,character
dbRemoveTable(conn, name, ...)
# S4 method for PqConnection,character
dbListFields(conn, name, ...)

Arguments

conn

a '>PqConnection object, produced by DBI::dbConnect()

name

a character string specifying a table name. Names will be automatically quoted so you can use any sequence of characters, not just any valid bare table name.

value

A data.frame to write to the database.

...

Other arguments used by individual methods.

row.names

Either TRUE, FALSE, NA or a string.

If TRUE, always translate row names to a column called "row_names". If FALSE, never translate row names. If NA, translate rownames only if they're a character vector.

A string is equivalent to TRUE, but allows you to override the default name.

For backward compatibility, NULL is equivalent to FALSE.

overwrite

a logical specifying whether to overwrite an existing table or not. Its default is FALSE.

append

a logical specifying whether to append to an existing table in the DBMS. Its default is FALSE.

field.types

character vector of named SQL field types where the names are the names of new table's columns. If missing, types inferred with DBI::dbDataType()).

temporary

If TRUE, will generate a temporary table statement.

copy

If TRUE, serializes the data frame to a single string and uses COPY name FROM stdin. This is fast, but not supported by all postgres servers (e.g. Amazon's redshift). If FALSE, generates a single SQL string. This is slower, but always supported.

RPostgres does not use parameterised queries to insert rows because benchmarks revealed that this was considerably slower than using a single SQL string.

con

A database connection.

check.names

If TRUE, the default, column names will be converted to valid R identifiers.

Examples

# NOT RUN {
# For running the examples on systems without PostgreSQL connection:
run <- postgresHasDefault()

library(DBI)
if (run) con <- dbConnect(RPostgres::Postgres())
if (run) dbListTables(con)
if (run) dbWriteTable(con, "mtcars", mtcars, temporary = TRUE)
if (run) dbReadTable(con, "mtcars")

if (run) dbListTables(con)
if (run) dbExistsTable(con, "mtcars")

# A zero row data frame just creates a table definition.
if (run) dbWriteTable(con, "mtcars2", mtcars[0, ], temporary = TRUE)
if (run) dbReadTable(con, "mtcars2")

if (run) dbDisconnect(con)
# }