Re: bitmap or fbi?

From: Daniel Morgan <damorgan_at_x.washington.edu>
Date: Sun, 11 Jan 2004 11:00:48 -0800
Message-ID: <1073847569.519520@yasure>

Bricklen wrote:

> Daniel Morgan wrote:
> 

>> Bricklen wrote:
>>
>>> I was playing with a function-based index (on 9r2), trying to get it
>>> to mimic the performance of one of my bitmap indices.
>>>
>>> fbi:
>>> create index t_fbi_fidx on t_fbi(
>>> case when <some criteria> then pkid else null end);
>>>
>>> then I tried this:
>>> create BITMAP index t_fbi_bidx on t_fbi(
>>> case when <some criteria> then pkid else null end);
>>>
>>> ...and to my surprise it worked. Does this make it a bitmap, or an fbi?
>>> Did I miss something in the manuals?
>>>
>>>
>>> Bricklen
>>
>>
>>
>> Take a look at the wire diagram at:
>> http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96540/statements_510a.htm#SQLRF01209
>>
>>
>> You will notice that (UNIQUE) and (BITMAP) are options.
>>

> Thanks for the link. So how would you classify the bitmap index with the 
> index_expression in the table_index clause? Simply as a bitmap index?
> 
> Thanks!

If I understand your question ... we just assume an index is B*Tree if someone doesn't say something just as we assume it is non-unique if someone doesn't say something.

So any change from the "default" should just be part of the description.

One can build a UNIQUE FUNCTION BASED INDEX or a BITMAPPED FUNCTION BASED INDEX. If someone has the time perhaps they can create add the DESCENDING keyword too and see what happens. ;-)

-- 
Daniel Morgan
http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp
http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp
damorgan_at_x.washington.edu
(replace 'x' with a 'u' to reply)

Received on Sun Jan 11 2004 - 13:00:48 CST