[R] Fwd: Cannot allocate a new database connection error

[Uwe Ligges]

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: (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.
> 
> 
> 
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