>>>>> "Carlos" == Carlos Mennens <carlos.mennens@gmail.com> writes:
Carlos> Looking to read your feedback and / or opinions.
Here's what I wrote on the Smalltalk Seaside mailing list a few weeks
back:
I've given a talk a few times about "forget the ORM". The slides are up
on http://www.slideshare.net/RandalSchwartz/forget-the-orm
The key thing that separates a lot of these newer databases is that you
can't have all three of consistency, availability, and performance at
once... you have to sacrifice something. Traditional SQL databases
favored consistency over everything, but who cares if your blog page
says "read the 6 comments on this item" for a couple of seconds when
there are really 7 because one just got added.
The new databases give options for higher availability or performance at
the cost of consistency. Some, like Riak (interviewed at
http://twit.tv/floss129), actually let you select on each request how
consistent you want the results, thus controlling how fast you get the
response. Thus, for the front page of a blog, you can say "give me a
result that any 1 of the 3 replicas has", but when you finally drill
into the comments, you say "give me a result that all 3 replicas agree
on". Of course, these are all *eventually* consistent on the order of
tens or hundreds of milliseconds, but by allowing "almost correct"
results, things are a lot zippier. (It also works that way on
write... you can say "come back when any 1 replica says it has it" or
"come back only when all 3 replicas confirm write".)
So, it's not so much that you get schemaless key/value store (although
that's a frequent feature)... it's that these aren't traditional
databases in a lot of ways.
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
See http://methodsandmessages.posterous.com/ for Smalltalk discussion