What is Multiversion Concurrency Control (MVCC) and who supports it? [closed]

Answer 1

There's a good explanation of MVCC -- with diagrams -- and some performance numbers for eXtremeDB in this article, written by McObject's co-founder and CEO, in RTC Magazine:

http://www.rtcmagazine.com/articles/view/101612

Clearly MVCC is increasingly beneficial as an application scales to include many tasks executing on multiple CPU cores.

Answer 2

PostgreSQL's Multi-Version Concurrency Control

As well as this article which features diagrams of how MVCC works when issuing INSERT, UPDATE, and DELETE statements.

Answer 3

Firebird does it, they call it MGA (Multi Generational Architecture).

They keep the original version intact, and add a new version that only the session using it can see, when committed the older version is disabled, and the newer version is enabled for everybody(the file piles-up with data and needs regular cleanup).

Oracle overwrites the data itself, and uses a rollback segments/undo tablespaces for other sessions and to rollback.

Answer 4

SAP HANA also uses MVCC. SAP HANA is a full In-Memory Computing System, so MVCC costs for select is very low... :)

Answer 5

XtremeData dbX supports MVCC.

In addition, dbX can make use of SQL primitives implemented in FPGA hardware.

Answer 6

SQL Server 2005 and up offer MVCC as an option; it isn't the default, however. MS calls it snapshot isolation, if memory serves.