On 2/27/07, Vegard Bønes <vegard.bones@xxxxxx> wrote:
Hi! I am writing a serverside function in plpgsql, which returns a part of a large object. To solve this problem I can do something like this: fd := lo_open( some_oid, 262144 ); PERFORM lo_lseek( fd, index, 0 ); RETURN loread( fd, read_size ); This works well enough, but I do feel slightly uneasy about using numbers instead of symbolic names (262144 for INV_READ and 0 for SEEK_SET). I do especially find SEEK_SET unsettling, since this constant is defined outside of postgresql, and it may therefore be defined to other values than 0 on other platforms. Am I missing something here? Is there a way to specify these names without writing the actual numbers, or should I just close my eyes and hope that everything will work?
You can make a preprocessor file for your sql stuff and pre-process all your sql using classic C defines for your constants. with little work you can even share headers with your applications. Major downside to this approach is you cannot copy/paste your function bodies (or any sql using macros) into psql/pgadmin, etc. You can use psql variables for similar things but unfortunately not inside functions bodies because they are strings :(. Ideally, for these type of problems I would like to use psql variables because it gives me more flexibility than the C preprocessor in terms of development. merlin
