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Re: [Bacula-devel] Alternative DB structures-Porposal


On Sep 24, 2008, at 4:56 PM, John Huttley wrote:

> Ok I've got a better handle on this.
> First, a side issue that anyone dealing with PG needs to know about.
>
> PG uses MVCC. This allows unlimited transactions in flight and is  
> lock-free.
> So it has great concurrency.
>
> But there is a draw back. Edit a row, and we get another version of  
> that row.
> Any indexes on that table have to updated, even if the field you are  
> updateing
> is not indexed (!!!!!!!!!)

No need for !!!!!!!!!.  :)  Of course great concurrency has a price.  :)

The goal, if we can, is to avoid any "insert update... update"  
strategies.

Any tests you do, I can help by duplicating the run on my servers.   
Being able
to duplicate your test results will help decide go/no-go with respect  
to design
consideration.

-- 
Dan Langille
http://langille.org/





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