[R] large object disorientation

Emmanuel Charpentier
Thu, 23 Nov 2000 17:19:30 -0000

> This is an inquiry for all those who have been working on external
> data base applications. I sent an inquiry (below) to snews about
> this sort of thing a couple of years ago and eventually decided that
> I would wait to see what external database developments occurred and
> then revisit the problem. I hope that foundations are now better.

[ "Concrete" exemple uncast for bandwith's sake ... ]

Well ... this points back to the "database interfaces" discussed here
a while
ago.

The closest present implementation of whazt you wish is, IMSAO, the RPgSql
package, which offers "proxy" databases objects. Depending of the
algorithms
used in your application, you might end up achieving what you aim at without
any special coding.

The drawback is obvious : if your data aren't in PostgreSQL, you're SOL
...

Another possibility, which requires explicit coding, is RODBC. In that package,
you have two levels of function : the "sqlXxxx" functions, which in
general
return a whole database object, and the "odbcXxxx" functions, which
allow you
to specify some SQL request and read the result back one row at a time.

Drawbacks : explicit coding necessary. Advantages : any ODBC-enabled database
for which you happen to have a driver will do.

Hope this helps ...

						Emmanuel Charpentier


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