On 1/16/11 1:14 PM, Alex Karasulu wrote:
Now, this is true for updates, not for searches which span over more than
one entry, which means the entries you get back may not be fresh when you
want to use them.
Isolation is non-existant allowing for dirty reads. We can solve this
issue though. It's going to take time and some evolution.
However, ADS has a few issues with ACIDity when it comes to manage APs, as
we update more than one entry when injecting a subentry. (I don't think
there are other oparations that need more than one update, but OTOH, a lot
of update operations do a lookup before doing a write).
SPs and Triggers will present these same issues.
Very true. This is an area we have to investigate, as it's more a
prototype right now than a completed feature.
AP is the first time we seriously hit a wall with this because we're
getting to complex scenarios that are requiring these multiple updates
to happen in an atomic way. There will be more cases in the future I'm
almost certain of this.
FTR, we fixed some ACID issues last year, when we reviewed all the
operations. The operational attributes were added after the entry was
stored in the
backend, leading to a potential breakage. Now, the op attrs are
injecting in the entry *before* being injected in the backend.
This was an issue we detected 4 years ago :
https://issues.apache.org/jira/browse/DIRSERVER-840
This is the reason we need a TM. Note that if we don't update the entries
when injecting a subentry, we are safe (this is option #1, btw)
Then a set of M2 releases can be made.
I would move that for M3 instead. We don't have a lot of background on TM
atm.
Actually this sounds a lot more difficult than it will be. We also
have a lot of the machinery available. We need txn log and some other
things.
However what I recommend is to do this in steps. Does not have to be
fully implemented in a single milestone release. We can just erect the
scaffolding and have the rest of the system using the API.
Across other milestones we can start filling in the implementation
with minimal impact to ADS SPI users.
<Snip/>
Right now, before discussing what will be in M7, I think the best is to
get M1 out with OSGi, some refactoring in shared, and as few possible
thing as possible !
Then we will be able to start discussing about what is in M2, then in
M3, etc... Let's not anticipate on the problem we will face anyway
before facing them :)
--
Regards,
Cordialement,
Emmanuel Lécharny
www.iktek.com
