Re: Indexes and Logical design

Christopher Browne wrote:
[...]
[VC]
> > Besides, sequential retrieval for a read/write transaction requires locks on
> > the entire table, which results in coarser locks and degraded concurrency.
>
> Not necessarily; alternative mechanisms exist, and are actively used.
>
> Pretty well any of the database systems still undergoing active
> development offer some variation of MultiVersion Concurrency Control
> (MVCC) where updates lead to creating new versions of tuples, which
> allows the reads, at least, to not require any locks...

Sorry, regardings locks, I should have made it clear that I was answering in the context of Rdb/VMS that does not have MVCC. The little known Rdb/ELN, of which Interbase is a cousin, does implement MVCC and your argument holds there.

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Received on Mon Sep 12 2005 - 14:44:43 CEST