Re: Index on partial field? No - so then?

>No
 

>Barbara Hiles <BEH_at_csd.uwm.edu> wrote in article
><BEH.727.0098F6FE_at_csd.uwm.edu>...
>> Is it possible to create an index using part of a field?
>> For example: 9 character ssn.
>> I need an index on last 4 first 5.
>> Can I do this if I've defined a 9 char ssn field? (and if so - how?
 substr?)
>>
>> tia - barb.

Ok - so I can't do that.
So how does everybody else handle this stuff? We're migrating from IMS to Oracle. We have segments indexed six ways to Sunday. We have IO mods that do db access and for expediency sake we are converting them (no way we're reengineering code - no time or money or staff).
What are the tradeoffs for not creating indexes? Do you try to figure out which indexes are used most? We can and have set up cursors in pl/sql to essentially create the index on the fly. I'm afraid that once the volumes and usage go up - this isn't going to work very well (we're not production yet).
So, I'm interested in comments on that.

Back to the field separation - I'm still struggling with this. Not just for indexing sake - but in general usage too. Several indexes need parts of key fields. Does anyone define a composite key and then repeat the fields individually? I would have to enforce this with triggers - I don't really like the idea much. But trying to find the next record greater than with a key made up of 5 separate fields gets kludgy.

If anybody can point me in other directions - I'm grateful for the help. Received on Wed Jan 29 1997 - 00:00:00 CST