>It does not look like a provider problem completely. That particular column, BYTES, is defined as type NUMBER with no precision or scale (run DESC User_Extents from a SQL*Plus prompt to see the structure). It lloks like Oracle does this same thing when doing a COUNT(*), etc. See my reply back to Aleksey on his questions to you.

Yes, your discussion with Aleksey was very enlightening ! For the moment, what looks like the best solution to me is to never use cursoradapters when querying the data dictionary, counts or sequence numbers, and to never use high precision fields in the business database (what I already knew was not recommended).
I am just surprised that the CAST to NUMBER(7,0) didn't work in my case, and that I get different values for Precision and NumericScale (255 and 255). My guess is that it is a difference between the Oraoledb (that I am using) and Msdaora (that you are using) Oracle providers. Do you recommend the latter over the former ?