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Querying Postgres or Greenplum From R on a Mac, Installation Instructions

NB: this works on 64b versions of R; I tested it with the R64 app with R version 2.10.1 on Snow Leopard

Step by step instructions for talking to Postgres or Greenplum:

  1. install macports
  2. install postgres; I used 8.4 via sudo port install postgresql84
  3. in a shell, create an environmental variable PG_CONFIG pointing to the pg_config binary installed by postgres. In my installation, this is something like export PG_CONFIG=/opt/local/lib/postgresql84/bin/pg_config
  4. in the same shell, tell R to install the RPostgreSQL package from source, ie > install.packages('RPostgreSQL', type='source')
  5. test the installation works:
> library('RPostgreSQL')
Loading required package: DBI
> drv <- dbDriver('PostgreSQL')
> db <- dbConnect(drv, host='greenplum.ip', user='earl', dbname='dbname')
> dbGetQuery(db, 'select 1')
1       1

Diagnosing error messages / problems:

  • If R says
Warning message:
In install.packages("RPostgreSQL") : package ‘RPostgreSQL’ is not available

you must specify to install the package from source, as above with type='source' * If you get compilation errors when installing the package that mention libpq-fe.h, then R can’t find pg_config * if the package installs but when loading it you get errors involving missing symbol _PQbackendPID then you are mixing 32 and 64 bit software.

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