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RODBC

2 messages · Emmanuel Charpentier, Brian Ripley

Emmanuel Charpentier
# 
I saw in the R-digest a thread about RODBC.

1) I think that this package is *extremely* valuable : it fulfills a need
quite important in the case of iterative (e. g. periodic) analyses. No need to
periodically return to your data and re-dumping them ...

2) The current version has a serious bug if your datasets has missing numeric
values. M. Lapsley, the original author, is aware of it, but has had no time
yet to look at it ...

I looked into the source to no avail. I'll have to dive in ODBC library
mysteries (which are pure Swahili to me ...), and did not yet had time for
this.

<OffTheTopOfMyHeadIDontHaveTheFilesOnHand>
In interim, you can uncomment the old (much less efficient) of the odbcQuery
routine, which does *not* exhibit this bug. Data are correct, speed seriously
sucks ...
</OffTheTopOfMyHeadIDontHaveTheFilesOnHand>

3) If you happen to use PostgreSQL, the RPgSql package (also on CRAN) is much
more interesting : it allows direct access to PostgreSQL classes (tables) as R
objects, ensuring that any R access is done to up-to-date data.

Of course, OTOH, if you happen to trash your R data-access-objects, your
original data are gone for good. Caveat emptor ...

4) IMNSHO, the future lies somewhere in the (hypothetical) fusion of these two
package : direct access to ODBC objects would be perfect (and might seriously
alleviate problems due to the R static memory allocation model, which is an
EPITA ...).

Hope this helps,

					Emmanuel Charpentier

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Brian Ripley
#
On Wed, 15 Nov 2000, Emmanuel Charpentier wrote:

            

      
      
      
    

        
I have tried in the last two days to reproduce it, and I just can't.
I've tried RODBC to MySQL on Windows, and RODBC to PostgreSQL on Unix.
Every time I get blank strings mapped to NAs, in numeric (right) or
character (wrong) fields, and I have a fix for the latter.

So can you tell me (and Michael L) exactly what you did?

            

      
      
      
    

        
What R static memory allocation model?  Take a look at R-devel....
Notwithstanding that, I agree and am beginning to use databases quite a
bit.  Of course, one then sees how to improve the interfaces ....

One thing R-1.2.0 will come with is a Data Import/Export manual covering
all the database access packages (and much else).  A draft is available
on the R developer site (http://developer.r-project.org/R-data.pdf)
if you want to take a look.  (Comments to me please, and it is not
completely finished yet, and that includes not completely checked yet.)