R help - May 2009 - Fwd: Cannot allocate a new database connection error

---------- Forwarded message ----------
From: Moumita Das <das.moumita.online@gmail.com>
Date: Sat, May 16, 2009 at 2:26 PM
Subject: Cannot allocate a new database connection error
To: r-help-request@r-project.org


Hi friends,
why do i keep getting this error?The program runs, twice and every third
time i get this error.I have to quit.Again get teh R-prompt and then run the
script.

*Error in mysqlNewConnection(drv, ...) :
  RS-DBI driver: (ì8@`qE@°
°
cannot allocate a new connection -- maximum of 16 connections already
opened)
Error in is(object, Cl) :
  error in evaluating the argument 'conn' in selecting a method for
function
'dbSendQuery'
Error in is(object, Cl) :
  error in evaluating the argument 'res' in selecting a method for
function
'fetch'*


*this is my DB connection function*
*myDbConnect <- function (dbName, hostName) {
      drv<-MySQL()
      con <- dbConnect(drv, user="xyz",
password="xyz",dbname = dbName, host
= hostName)
    return(con)
}*


everytime i need ,Db connection , i used in this way:----



This is the structure of my code:--
main <- function ()
 {
          #Looping through subgroups
           for(sub_group_num_loopcounter in 1:sub_group_num_data_size[1])
           {
             #Fetching the where clause for the particular subgroup
*            sub_group_where_condition <-
fetch(dbSendQuery(myDbConnect(dbName,hostName), paste(c("SELECT
where_clause
FROM sub_grp where

num=",sub_group_num_data[sub_group_num_loopcounter,1]),collapse="")),
n -1)  *
            }
            dbDisconnect(con)
            dbListConnections(MySQL())
            l<-list()

}

Where should i close the DB connection  or use one single connection
throughout the prograam.

-- 
Thanks
Moumita



-- 
Thanks
Moumita

	[[alternative HTML version deleted]]

Open a connection as in

con <- myDbConnect(dbName,hostName)

before the loop starts and afterwards just work on "con".

Uwe Ligges






Moumita Das wrote:
> ---------- Forwarded message ----------
> From: Moumita Das <das.moumita.online at gmail.com>
> Date: Sat, May 16, 2009 at 2:26 PM
> Subject: Cannot allocate a new database connection error
> To: r-help-request at r-project.org
> 
> 
> Hi friends,
> why do i keep getting this error?The program runs, twice and every third
> time i get this error.I have to quit.Again get teh R-prompt and then run
the
> script.
> 
> *Error in mysqlNewConnection(drv, ...) :
>   RS-DBI driver: (?8@`qE@?
> ?
> cannot allocate a new connection -- maximum of 16 connections already
> opened)
> Error in is(object, Cl) :
>   error in evaluating the argument 'conn' in selecting a method for
function
> 'dbSendQuery'
> Error in is(object, Cl) :
>   error in evaluating the argument 'res' in selecting a method for
function
> 'fetch'*
> 
> 
> *this is my DB connection function*
> *myDbConnect <- function (dbName, hostName) {
>       drv<-MySQL()
>       con <- dbConnect(drv, user="xyz",
password="xyz",dbname = dbName, host
> = hostName)
>     return(con)
> }*
> 
> 
> everytime i need ,Db connection , i used in this way:----
> 
> 
> 
> This is the structure of my code:--
> main <- function ()
>  {
>           #Looping through subgroups
>            for(sub_group_num_loopcounter in 1:sub_group_num_data_size[1])
>            {
>              #Fetching the where clause for the particular subgroup
> *            sub_group_where_condition <-
> fetch(dbSendQuery(myDbConnect(dbName,hostName), paste(c("SELECT
where_clause
> FROM sub_grp where
> 
>
num=",sub_group_num_data[sub_group_num_loopcounter,1]),collapse="")),
n > -1)  *
>             }
>             dbDisconnect(con)
>             dbListConnections(MySQL())
>             l<-list()
> 
> }
> 
> Where should i close the DB connection  or use one single connection
> throughout the prograam.
> 
> 
> 
> ------------------------------------------------------------------------
> 
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