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Re: Much Ado About COUNT(*)

From: Sailesh Krishnamurthy <sailesh(at)cs(dot)berkeley(dot)edu>
To: "Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>
Cc: Andrew Dunstan <andrew(at)dunslane(dot)net>, tgl(at)sss(dot)pgh(dot)pa(dot)us,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Much Ado About COUNT(*)
Date: 2005-01-18 20:45:50
Message-ID: mjqvf9uzcsh.fsf@drones.CS.Berkeley.EDU (view raw or flat)
Thread:
Lists: pgsql-announcepgsql-hackerspgsql-patches
>>>>> "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.

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



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