The adopted Bitmap

This is a running example of the article in DC on Bitmap Adoption

The full background story is found there.

The base class Bmap.Person defines persons within an organization distributed
by various countries. All records are indexed by (Country, PersonalId).
this structure doesn’t allow use of bitmaps.

So a wrapper class Bmap.PersonQ around the data eliminates the top level of
the index (Country) and isolates the PersonalId (%Integer, MINVAL=1).
We are ready to use a Bitmap index.

A few performance figures on 300010 generated records.
You see that Relative Cost are sometimes quite misleading.

base

  select count(*) from Bmap.Person  
  300010 global references 1600446 lines executed   

demo 1

  select count(*) from Bmap.Person where Ctry='RU'  
  Relative cost = 197762  
  10015 global references 70474 lines executed    
select count(*) from Bmap.PersonQ where Bmap.Ctry('RU')=1

Relative cost = 401400

10 global references 424 lines executed

demo2

  select count(*) from Bmap.Person   
     where Ctry='RU' and home_state='MA'   
  Relative cost = 457.96    
  218 Global references 2335 lines executed   
select count(*) from Bmap.PersonQ

where Bmap.Ctry('RU')=1 and home_state='MA'

Relative cost = 2012.8

16 global references 478 lines executed

demo3

  select home_state,count(*) from Bmap.Person   
     where Ctry='RU' group by home_state  
  Relative cost = 372162   
  Row count: 50 Performance: 0.027 seconds   
  10420 global references 153708 lines  
select home_state,count(*) from Bmap.PersonQ

where Bmap.Ctry('RU')=1 group by home_state

Relative cost = 453400

Row count: 50 Performance: 0.018 seconds

817 global references 155475 lines executed

Article in DC