In Firebird-general@yahoogroups.com,
Dmitri Kouzmenko <kdv@i...> wrote:

> p> I was engaged in a debate about IB/FB's
> p> MVCC model and various other issues about


> Need some correction. InterBase's multiversion
> architecture is named as Multi-Generational Architecture
> (MGA). So, most of documents about Interbase refer to
> MGA, not MVCC.

Aw, come on! That's just semantics, whether we
call it MVCC, MGA or record-shadowing or
record-versioning or Row Versioning. 8-)

I've just thought of a nice definition -
record-piggybacking. Any takers?

> - Oracle have versioning (named as semi-verisioning
> because it have some problems with very long snapshot
> transactions) since version 8.0 (am I right?).

I think it's ORA-1555 (or something like that) is
the error if your undo log gets too big. Their
architecture does allow for PITR though.

I think they had a read version of MGA since
version 4 but the whole system only became
MGA since 7 - but I can't remember where I
read this - have been reading a lot of
different sites about this.

> - PostgreSQL have MVCC since ... (don't know).

unable to find this. I don't think it
was there from day 1 though - but can't
find site.

Here
http://pgsqld.active-venture.com/history.html

It seems to imply that there used to be
a locking mechanism but that it was
replaced in and around 1995, but it's
not that clear.

> - MS SQL 2005 will have versioning same as in
> InterBase/Firebird.

Will be similar (if ever realeased) as Yukon.
Many went there, most died poor and cold.

> - MySQL will (? or already) have versioning ... don't know
> about it's implementation or limitations.

If Oracle let them!!! Oracle bought their
versioning engine supplier.

Microsoft motto - Embrace and Extend (meaning
smother)
Oracle motto - Buy, buy, buy (to competitors),

you may or may not get the pun in English,
"Bye, bye, bye (to competitors)".


Check out the URL in the thread I posted to

http://dev.mysql.com/doc/refman/5.0/
en/innodb-multi-versioning.html

And then check out Roman Rottsky's article
and you will see that they're virtually
identical.

> These all show that commercial RDBMS' are moving to
> versioning systems. And this also shows that
> there is no new (extraordinal) thoughts in that area
> since 1983-1985.

Relational model - 1970 - no significant improvements
since - ditto for MGA 1980.


Paul...

> Dmitri Kouzmenko, www.ibase.ru, (095) 953-13-34