[R] RMySQL query: why result takes so much memory in R ?

[Christoph Lehmann]

Hi
I just started with RMySQL. I have a database with roughly 12 millions 
rows/records and 8 columns/fields.

 From all 12 millions of records I want to import 3 fields only.
The fields are specified as:id int(11), group char(15), measurement 
float(4,2).
Why does this take > 1G RAM? I run R on suse linux, with 1G RAM and with 
the code below it even fills the whole 1G of swap. I just don't 
understand how 12e6 * 3 can fill such a huge range of RAM? Thanks for 
clarification and potential solutions.


## my code
library(RMySQL)
drv <- dbDriver("MySQL")
ch <- dbConnect(drv,dbname="testdb",
                 user="root",password="mysql")
testdb <- dbGetQuery(ch,
        "select id, group, measurement from mydata")
dbDisconnect(ch)
dbUnloadDriver(drv)

## end of my code

Cheers
Christoph