Re: Much Ado About COUNT(*)

>>>>> "Jonah" == Jonah H Harris <jharris(at)tvi(dot)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't seem
Jonah> logical to me that commercial database companies would
Jonah> spend money on implementing this feature if 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.

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Sailesh
http://www.cs.berkeley.edu/~sailesh