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Re: MVCC implementation

From: Cimode <cimode_at_hotmail.com>
Date: 21 Jul 2006 09:11:20 -0700
Message-ID: <1153498280.454510.326480@h48g2000cwc.googlegroups.com>


MVCC is just another buzz word for a set of principle applied to guarantee a limited integrity during transactions server level interactions. One example is row versioning. Implemented in ORACLE as Read Consistency and SQL2005 as READ_COMMITED_SNAšPSHOT. The principle is to make sure that all transactions always have access to the last version of commited data so that the SELECT's always read commited versions of the data, no matter what transaction are currently on hold.

It is light years from being a decent relational implementation even if it claims a noble goal which is integrity preservation. I do not see how an implementation could compensate for loss of integrity at transactionnal level when it ignores the most important : integrity at definition level

Marshall wrote:
> Hi all,
>
> Am I correct in regarding MVCC as pretty much the state of the art
> for relational implementation? (I know we hear things about TRM
> but until there's more published it doesn't seem evaluable.)
>
> Are there any difficulties associated with MVCC implementations
> supporting nested transactions?
>
> Any good references for reading about MVCC implementation?
> It's not clear to me how it works. Googling for it is doesn't get
> me any good references; mostly manuals for SQL products
> that support it. I'm interested in learning about how to code
> one up.
>
>
> Marshall
Received on Fri Jul 21 2006 - 11:11:20 CDT

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