[R] Setting the value of max in calls to sqlGetResults

[Alex Chelminsky]

I have compiled and linked a 64 bit version of R (R 2.9.2) and the
corresponding unix ODBC 64 bit package

When issuing a SqlQuery, I get the following error

> library(RODBC)
> channel <- odbcConnect("OraLSH", <user>, <password>)
> sqlQuery(channel,"select sysdate from dual")
Error in .Call(C_RODBCFetchRows, attr(channel, "handle_ptr"), max,
buffsize,  :
  negative length vectors are not allowed
> close(channel)
> q()

I know I can replace the call to sqlQuery with calls to its component
functions odbcQuery and sqlGetResults to get the same result (and the same
error)

> library(RODBC)
> channel <- odbcConnect("OraLSH", <user>, <password>)
> odbcQuery (channel, "select sysdate from dual")
> sqlGetResults(channel, as.is=FALSE, errors=FALSE, max=0, buffsize=1,
nullstring=NA, na.strings="NA", believeNRows=TRUE, dec=getOption("dec"))
Which returns the same error, namely:
Error in .Call(C_RODBCFetchRows, attr(channel, "handle_ptr"), max,
buffsize,  :
  negative length vectors are not allowed
>

However, if I modify the value of max=0 (which means there is no limit to
the number of rows that can retrieved) to another value, the function
returns the correct value:

> library(RODBC)
> channel <- odbcConnect("OraLSH", <user>, <password>))
> odbcQuery (channel, "select sysdate from dual")
> sqlGetResults(channel, as.is=FALSE, errors=FALSE, max=1, buffsize=1,
nullstring=NA, na.strings="NA", believeNRows=TRUE, dec=getOption("dec"))
              SYSDATE
1 2010-01-24 15:10:02
>

The issue is that, before issuing the query, I don't know how the size of
the resulting data frame. My question is: Is there a way to obtain the
value of the resulting data frame and using that as an argument to the max
parameter?


Alexander Chelminsky
Principal
CSC

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achelminsky at csc.com | www.csc.com

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