[R] Java Exception error while reading large data in R from DB using RJDBC.

[Jessica Streicher]

I didn't have the same exception yet, but please make sure you have a stable connection (avoid wlan).
I personally ran out of memory very often and had to make several queries, combining the results in R instead.

This is probably not the best thing to do, but worked for me to fetch large amounts of data, though it takes a while:
	
res<-dbSendQuery(conn,query)
result<-list()
i=1
result[[i]]<-fetch(res,n=100000)
while(nrow(chunk <- fetch(res, n = 100000))>0){
	i<-i+1
	result[[i]]<-chunk
}
allResults<-do.call(rbind,result)

On 30.10.2012, at 12:32, aajit75 wrote:

> Dear List,
> 
> Java Exception error while reading large data in R from DB using RJDBC.
> I am trying to read large data from DB table(Vectorwise), using RJDBC
> connection.
> I have tested the connection with small size data and was able to fetch DB
> tables using same connection(conn as in my code).  
> 
> Please suggest where  am i going wrong or alternate option to solve such
> issues  while reading large DB table.
> 
> drv <- JDBC(paste(db_driver,  sep = ""),
>           paste(db_jar_file,  sep = ""),
>           identifier.quote="`")
> 
> conn <<- dbConnect(drv, paste(db_server,  sep = ""),
> 					paste(db_server_lgn,  sep = ""), 
> 					paste(db_server_pwd,  sep = ""))
> s <- sprintf("select * from  cypress_modeldev_account_info")
> temp <- dbGetQuery(conn, s) 
> Error in .jcheck() : 
>  Java Exception <no description because toString() failed>.jcall(rp, "I",
> "fetch", stride)<S4 object of class "jobjRef">
> 
> 
> 
> 
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