Выбегаллоинтересные новости...
А мне больше понравилось вот это:
The merge of IDS and DB2 has been canceled.
Both data servers will be developed and promoted independently from each other.

Выбегалло
Lаst commited concurrency внешне похоже на версионность, но с глубиной отката в только одну транзакцию. Честно говоря, слабо представляю, зачем это нужно и как это будет работать.
Как зачем ? Чтобы не говорили, что в Информиксе "писатель мешает читателю" :)

Andron CNews: IBM раскрывает подробности о сервере данных IDS Cheetah
Увы, но никаких "подробностей" там нет - обычная маркетинговая шелуха, а заголовки в инете - это "отдельная песня" :)

Выбегалло... Особеннно про 2 новых уровня изоляции -
Last committed concurrency:
...
Optimistic concurrency:
...
Lsst commited concurrency внешне похоже на версионность, но с глубиной отката в только одну транзакцию. Честно говоря, слабо представляю, зачем это нужно и как это будет работать.
Чтобы " Reads don't block writes and writes don't block reads and only сommitted rows are visible ."
Увидел статью на эту тему, возможно вам будет интересно:
"Cheetah spot by spot: LAST COMMITTED READ" (Fernando Nunes)
http://informix-technology.blogspot.com/2007/02/cheetah-spot-by-spot-last-committed.html
а также некорые комментарии автора в CDI

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> I have been under the impression that this one feature is what Oracle sells
> to clients, that they have the best non-blocking database engine available.
> Perhaps this is a bit simplistic, but it is notable that applications and
> developers now have another choice of what engine to use if indeed this is
> similar to the Oracle implementation, and was not available in other
> products.
I'm not speaking for IBM... standard disclaimer applies, but:
In practice, I think this has the same results. Using this, you won't block
when trying to read a row that has a lock (not a shared one, but an
insert/update/delete lock). You will get whatever was there (or wasn't...)
before the operation holding the lock.

However, the underlying implementation is AFAIK (I'm not a developer...)
completely different. Oracle is a versioned RDBMS like Postgres and I believe
some engines used in mySQL. Informix is NOT. The Informix implementation is
simpler (quicker?). If it hits a lock, it fetches the value from logical logs.

SQL server has a similar implementation if I read and understood it's
documentation correctly (since v2005 if I recall correctly).

From my experience as DBA, this is THE feature that developers were wishing
for. From some talks with colleagues and some customers I don't find the degree
of enthusiasm I was expecting...

I'll be very happy if my daily customer migrates to IDS 11 and I can use this
feature. I'm "tired" of explaining the locking issues to developers that were
trained only in Oracle...

It will also make my daily discussions (friendly) with an Oracle DBA much less
boring, since we tend to fall in this specific difference :)
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