[gnome-db] Reading LOBs with the Oracle backend

[Magnus Bergman <magnus bergman observer net>]

Currently there is no completely functional support for reading LOBs in
the Oracle backend in libgda (no other data database abstraction
library, except Perl, seams to support it either).

The problem is this: Then reading a row from the Oracle database you
first have to allocate enough memory for it. This is done by
requesting the maximum size of each column and allocate this amount of
memory. So far everything is fine. But then it comes to LOBs this
doesn't work. What is reported as the maximum size for a LOB column
then? Some parts of the documentation say -1, others 0, yet others say
4. But I get 32767. If a buffer of 32767 bytes is allocated (I guess
this is what happens in libgda) it works sometimes and crashes
sometimes (or just doesn't work). The actual maximum size is far beyond
that of course so it doesn't really make sense to allocate that much
memory.

The right way to do this is to not read the contents of the LOB,
but read the field as a LOB handle instaed. And at a later stage use
the LOB handle to get the size of the LOB and read it's contents.
Perhaps I could fix this if somebody tells me in which function(s) this
should be handled.