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Home -> Community -> Usenet -> c.d.o.server -> Re: Another angle on this....
On 19 Feb 2002, tom.mcclelland_at_mondas.com wrote:
> damorgan <dan.morgan_at_ci.seattle.wa.us> wrote in message
>> 1. No multiversioning.
Basically, all databases will have a rollback or undo capability. Oracle goes through great but very clever steps to use this rollback facility in a very powerful way. User A starts a transaction and updates row X. After this transaction starts, User B queries for row X. Oracle sees that this row has been updated but not committed. It therefore performs a rollback on this data for User B only. User B gets the before picture of row X. All other users will get the same treatment. Therefore, Oracle is maintain multiple versions of the same data. This makes it so that writers do not block readers. SQL Server will not allow User B to see Row X until it has been committed.
-- Galen deForest Boyer Sweet dreams and flying machines in pieces on the ground.Received on Fri Mar 01 2002 - 21:19:15 CST
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