Sure.  -bryan


From: [] On Behalf Of Kevin Day
Sent: Thursday, March 30, 2006 5:02 PM
To: JDBM Developer listserv
Subject: re[2]: [Jdbm-developer] re[14]: 2PL: transactions, threads < s ni p>




If there is an opportunistic mechanism as a fall back, then it should be possible to make it occur on a per-tx basis... 


Obviously, mixing the two locking modes at the same time would not provide the full bennefit of either, but it may be nice to be able to flip between the two modes...  for example, run in optimistic mode until some ratio of aborts per started transactions is crossed, then flip to 2PL for a time, then flip back...


- K



I am not sure that you can do this on a per-transaction basis.  If you are not using the same lock/queue objects, then you are not going to be able to coordinate across transactions.  I think that this could be an architectural choice for an application, but not a per-tx choice. -bryan

From: [] On Behalf Of Alex Boisvert
Sent: Thursday, March 30, 2006 12:22 PM
To: 'Kevin Day'
Cc: JDBM Developer listserv
Subject: Re: [Jdbm-developer] re[14]: 2PL: transactions, threads < s nip>
'Kevin Day' wrote:  

So....  do we need to implement 2PL at the jdbm level?  Or do we use optimistic, and tell developers that they have to use locking at the application level if they want to avoid rollbacks for highly contended records?
I think this should be a pluggable policy that could be set of a per-transaction basis.

alex <


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