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README

About the RPostgreSQL package:

    Database Interface between R and PostgreSQL

For details, see the Adobe PDF file "DBI.pdf" in the doc folder or see the
documentation using help(PostgreSQL).  Examples provided in the devTests
folder illustrate some of the functionality.

=============================================================================

Basic usage:

  ## initialize the driver to PostgreSQL
  drv <- dbDriver("PostgreSQL")

  ## create a connection to a PostgreSQL server
  con <- dbConnect(drv, user="userName", password="123456",
                   dbname="gsoc", host="10.23.34.23")

  ## run a query, and get the result set as a dataframe
  dFrame <- dbGetQuery(con, "select * from someTable LIMIT 50")

  ## run a query, leave results in the library*
  ## note current implementation does not leave the result in the Server
  ## and there is no benefit using dbSendQuery() fetch() pair other than
  ## compatibility.
  rs <- dbSendQuery(con, "select * from someTable")

  ## fetch up to, say, 50 records
  dFrame <- fetch(rs, n = 50)

  ## close resultSet rs 
  dbClearResult(rs)

  ## close connection con
  dbDisconnect(con)

  ## Unload the driver drv
  dbUnloadDriver(drv)

For a more complete example, refer to the file demo.r in the devTests folder.

=============================================================================

Important Information:

1. The present version of RPostgreSQL can handle only one resultset per connection.
   Thus dbSendQuery/fetch usually do not have speed merit over dbGetQuery.

=============================================================================

Frequently Asked Questions (FAQ):

1.  What is Database Interface(DBI) ?

    The Data Base Interface (DBI) provides a layer of abstraction between R
    and relational databases. All the classes in the DBI package are virtual
    and need to be implemented using the various DBMS libraries. The vendor
    has written some functions for communicating with the database in some
    language like C, compiled the functions and the compiled code is the
    library. We write a C program that calls the functions in the library,
    when it wants to access the database. Every database library is
    different. The names of the functions vary, and the order in
    which you call them varies, and the details of passing queries to the
    functions and getting the data back out will vary. To manage this, DBI
    was extended for individual database back-ends MySQL, SQLite, Oracle,
    PostgreSQL via R packages ROracle, RMySQL, RSQLite and RPostgreSQL. 
    DBI for R-language was initially developed at Bell Labs by David James.

2.  What is RPostgreSQL ?
 
    The RPostgreSQL package provides a glue between the PostgreSQL database
    and the DBI of R. The C programming interface called libpq was used for
    communicating with PostgreSQL. 

3   What is libpq ?

    libpq is the C application programmer’s interface to PostgreSQL. libpq is
    a cross platform library providing set of library functions that allow
    client programs to pass queries to the PostgreSQL backend server and to
    receive the results of these queries.

4.  What about Rdbi/RdbiPgSQL ?

    Rdbi and RdbiPgSQL are a 'fork' of the DBI interface for R. RPostgreSQL follows
    the DBI as do ROracle, RMySQL and RSQLite.


For any queries,suggestions and comments, mail: 
 
    rpostgresql-dev@googlegroups.com

For security issues that should not directly go to public,
you may contact:

    Tomoaki Nishiyama <tomoakin@kenroku.kanazawa-u.ac.jp>
    Neil Tiffin <neilt@neiltiffin.com>
    Joe Conway <mail@joeconway.com>
    Dirk Eddelbuettel <edd@debian.org>
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