Re: Index on columns that have total of more than 255

Forgive my pointing this out, but a 255 long index defeats the purpose of indexing. The concept is to have a small copy of the table with just some primary identifier that you can check against - if that turns out to be 255 then you wind up getting four whole indexes per 1K page (ok 8 for some of us and 16 for others) - before you count in the overhead. At that point it is going to be about just as fast to read the table sequentially as it will be to do a btree based on a key that long. I don't know what the application is, but you should reconsider the model it is based on if it requires keys that long. As to why you can't? Everybody has limits - it would appear as though ours are too low in this case. Generally I start screaming at the modeller when the length of an index gets as high as 20 - 255 is beyond my comprehension. cheers j. At 12:31 PM 10/16/97 -0500, you wrote: }Greetings, } }We have this client software that was developed using Oracle and }we have this table that the total bytes of the primary key is more than }255. Oracle allowed us to do the above subject. }When we export the database from Oracle to Informix, I am getting }an error "517: The total size of the index is too large or too many }parts in index." on this table. } }My question is why I cannot do the above subject on any of the }Informix database? } }Thanks for the answer(s) in advance. } } }Aerial } }