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

From: christian schulz <ozric_at_web.de>
Date: Tue 03 May 2005 - 02:19:39 EST

Hi,

IMHO you need only when your columns are numeric X rows /100/100/8 MB.
 >>(12000000*3)/100/100/8
[1] 450

But one of your columns is group char. I'm suffering in the past in lot of things with massive data and R and recognize doing how many as possible in the database, or you have to upgrade your computer to 2-4GB like a database machine!?

regards, christian

Christoph Lehmann schrieb:

> 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
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue May 03 02:23:41 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:31:32 EST