nikosv wrote:

I suppose that might be a problem if you are porting an application
that has depended on some otherwise undesirable quirk of locking, but I
can't see it as a valid criticism of MVCC. (But as I say, it looks like
Ingres is going to give us the option to lock or to use MVCC.)

--
Roy

UK Ingres User Association Conference 2010 will be on Tuesday June 8 2010
Go to http://www.iua.org.uk/join to get on the mailing list.

On Jul 16, 2009, at 5:03 PM, Roy Hann wrote:

Both of you are assuming the average programmer can spell the word
"concurrency". Not so. They don't care. So either they code infinite
retry loops into their programs or they let the user see a nice error
dump on
the screen.

But worst of all, many web programmers don't consider concurrency and
the
"last writer wins" rules the roost, which only makes business sense on
another planet. They often get away with it because their
applications are
"shopping cart" type things where there is generally only one writer
of the
shopping cart data. I refer to this as data that is "vertically
partitioned
by creator".

Switching to MVCC will probably fix broken stuff described in my first
paragraph. It won't help the problems in the second paragraph. But it
won't hurt them either.

Again, the oblivious programmer wins. With MVCC, the customer gets some
kind of win. The whole thing is still a house of cards, but a more
predictable
one.

*Sigh*

Every time I start to worry about this stuff, I want to start drinking
large
amounts of Tequila. Or grain alcohol.

Lastly, there is some hope. The new web frameworks like Grails
include this
nice O/R mapping tool layered on Hibernate that encourages the use of
a "version"
column and uses it for optimistic locking. On top of that, Grails
actually
has a transaction manager and treats a very complex operation as a ...
*gasp*
.... TRANSACTION. Imagine that. AND Grails/GORM encourages FOREIGN
KEYS, unlike
the nasty O/R mapping in Ruby. The heresy continues! CGI programmers
are
turning over in their graves.

Pretty soon, data modeling will be back in vogue! Erwin sales will
skyrocket!

*BANG*

I woke up.

;-)

Cheers,

Michael Leo
Director of Managed Services
Kettle River Consulting

MLeo (AT) KettleRiverConsulting (DOT) com

Mike Leo wrote:

Ohhh, let me assure you I assume NO such thing!

[snip]

Hmm. I'm going to have to take a look at that. Every time I've looked
at web frameworks in the past I've got kind of queasy.

I honestly don't know what ERwin (or ER modelling of any kind) has to do
with database design. It is totally counterproductive IMO. That whole
industry is based on misconceptions, fallacies, and blindness. But that
is another rant for another time.

--
Roy

UK Ingres User Association Conference 2010 will be on Tuesday June 8 2010
Go to http://www.iua.org.uk/join to get on the mailing list.