Re: Much Ado About COUNT(*)

>>>>> "Jonah" == Jonah H Harris <jharris@tvi.edu> writes:
   Jonah> Replying to the list as a whole:
   Jonah> If this is such a bad idea, why do other database systems   Jonah> use it?  As a businessperson myself, it
doesn'tseem   Jonah> logical to me that commercial database companies would   Jonah> spend money on implementing this
featureif it wouldn't be   Jonah> used.  Remember guys, I'm just trying to help.
 

Systems like DB2 don't implement versioning schemes. As a result there
is no need to worry about maintaining visibility in
indexes. Index-only plans are thus viable as they require no change in
the physical structure of the index and no overhead on
update/delete/insert ops. 

I don't know about Oracle, which I gather is the only commercial
system to have something like MVCC.

-- 
Pip-pip
Sailesh
http://www.cs.berkeley.edu/~sailesh