Recently I successfully stored a 3GB BLOB in PostgreSQL V9.6.1 via psql-odbc V09.05.0400, but I was not able to read it afterwards. I got the error message "Error reading from large object." for the very first SQLGetData call. I debugged it and found out that psql-odbc uses "lo_lseek" and "lo_tell" in "lobj.c" which limit the amount of data to 2GB (int32 usage). In "lobj.c" there is even the comment /* XXX: Should we use lo_lseek64? */ and /* XXX: Should we use lo_tell64? */.
I temporarily changed the code to use lo_lseek64 and lo_tell64 and I could read the 3GB BLOB.
On what OS are you working? Could you test my code?
So, could you please change the official psql-odbc to use lo_lseek64 and lo_tell64?
It tells that the 64-bit functions are not supported prior to PostgreSQL V9.3. My suggestion would be either dropping the support for old versions or a dynamic switch between the 64-bit and the 32-bit functions based on the server version.
