Re: MVCC implementation

From: David Cressey <dcressey_at_verizon.net>
Date: Sat, 22 Jul 2006 13:42:10 GMT
Message-ID: <SWpwg.2469$qZ2.1735@trndny01>

"Cimode" <cimode_at_hotmail.com> wrote in message news:1153498280.454510.326480_at_h48g2000cwc.googlegroups.com... Quote:

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_SNA¨PSHOT. 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

End quote.

What is the connection, if any, between SQL2005 READ_COMMITTED_SNAPSHOT and Snapshot transactions as implemented in DEC Rdb version 1 in 1984? Are these different concepts?
Are they similar concept independently conceived? Or is there a track from the DEC RDb implementation to the SQL 2005 definition?

Can someone who knows both SQL 2005 and DEC Rdb's history answer this? Received on Sat Jul 22 2006 - 08:42:10 CDT