So, locking imposes an ordering constraint on the execution of transactions but the data view is governed by MVCC?

 


From: jdbm-developer-admin@lists.sourceforge.net [mailto:jdbm-developer-admin@lists.sourceforge.net] On Behalf Of Kevin Day
Sent: Tuesday, April 04, 2006 1:00 PM
To: JDBM Developer listserv
Subject: re[10]: [Jdbm-developer] re[2]: DefaultTransactionManager - dr aft of prototype.

 

Bryan-

 

Locking provides transaction serialization isolation only.  Read Uncommitted, Read Committed and Repeatable Read are entirely provided by the MVCC layer.

 

- K

 

 

>
Expand on this please.  What is the role fulfilled by locking in this design? -bryan
 


From: jdbm-developer-admin@lists.sourceforge.net [mailto:jdbm-developer-admin@lists.sourceforge.net] On Behalf Of Kevin Day
Sent: Tuesday, April 04, 2006 10:40 AM
To: JDBM Developer listserv
Subject: re[8]: [Jdbm-developer] re[2]: DefaultTransactionManager - dr aft of prototype.
 

Bryan-

 

This is completely different with MVCC.  Transactions operate in complete isolation from each other, regardless of what type of locking you use.

 

In the proof of concept I've put together, you can release locks whenever you want without violating isolation.  Locking is only necessary to ensure serializability.

 

Nice, eh?

 

- K 

  
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