Jeff,
Thank you for your response. Upon your suggestion, I sent the connection info
to the slaves as:
mpi.bcast.Robj2slave(sqlUser)
mpi.bcast.Robj2slave(sqlPass)
mpi.bcast.Robj2slave(sqlDBname)
mpi.bcast.Robj2slave(sqlHost)
and then inserted the following command in the slave task:
con <- dbConnect(MySQL(), dbname=sqlDBname, user=sqlUser, password=sqlPass,
host=sqlHost)
The slaves are executing the tasks before this command. However, they
failed to perform the tasks after this and even failed to run simple
SQL queries.
I also tried inserting a direct R command into the slave task as:
con <- dbConnect(MySQL(), dbname="XXXXX", user="XXXX", password="XXXX",
host="localhost")
But it is of no use. Please let me know if any one has suggestion for this
problem.
Thank you,
Krishna.
> Subject: Re: [R] RMySQL and RMPI together
> From: jdnew...@dcn.davis.ca.us
> Date: Mon, 19 Jul 2010 07:53:24 -0700
> To: kdbondalap...@jacks.sdstate.edu; r-help@r-project.org
>
> Don't send the open connection object... send the connection info (database
> name, username, password, etc.) and create new connections as part of the
> slave task. The master connection object is not valid on the slaves.
>
> kdbondalap...@jacks.sdstate.edu wrote:
>
> >
> >Dear R-users,
> >
> >I got problem when using both RMPI and RMySQL together and I thought some
> >body in this forum can help me.
> >
> >I have a huge data set (more than 300,000 rows) and I would like to modify
> >only few observations. I wrote the modifications in a function form and able
> >to send the function to slaves using Robj2slaves from RMPI package. However
> >the function needs MySQL data base name to extract the required
> >observations. I used the following ways to transfer the data base name to
> >salves:
> >
> >con <- dbConnect(MySQL(), dbname="XXXXX", user="XXXX", password="XXXX",
> >host="localhost")
> >
> >Method 1: mpi.bcast.cmd(con)
> >
> >Method 2: mpi.bcast.cmd(con <- dbConnect(MySQL(), dbname="XXXXX",
> >user="XXXX",
> >password="XXXX", host="localhost"))
> >
> >
> >But both didn't work. I can not send the complete table in my data base to
> >all slaves as it takes so much memory. In addition, the funtion had SQL
> >queries to extract the required observations to perform the analysis and to
> >send them back to the data base. Since I am not able to send the data base
> >name ('con' in this case) to slaves, slaves are not executing the function.
> >
> >Thank you,
> >Krishna.
> >
> >
> >
> >
> >
> >Krishna D Bondalapati
> >Research Associate
> >
> >Plant Science Department
> >
> >South Dakota State University
> >
> >
> >
> >
> >
> >
> >
> >
> > [[alternative HTML version deleted]]
> >
> >______________________________________________
> >R-help@r-project.org mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help
> >PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> >and provide commented, minimal, self-contained, reproducible code.
>
> ---------------------------------------------------------------------------
> Jeff Newmiller The ..... ..... Go Live...
> DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
> Live: OO#.. Dead: OO#.. Playing
> Research Engineer (Solar/Batteries O.O#. #.O#. with
> /Software/Embedded Controllers) .OO#. .OO#. rocks...1k
> ---------------------------------------------------------------------------
> Sent from my phone. Please excuse my brevity.
[[alternative HTML version deleted]]
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