On Tue, May 5, 2009 at 8:50 AM, Kevin Grittner
<Kevin.Grittner@wicourts.gov> wrote:
> While discussing potential changes to PostgreSQL documentation of
> transaction isolation levels, Emmanuel Cecchet pointed out an
> intriguing new paper[1] on a new algorithm to provide true
> serializable behavior in a MVCC based database
I agree, this is very interesting work. I blogged about it a while ago[1].
> "Making these changes to Berkeley DB involved only modest changes to
> the source code. In total, only 692 lines of code (LOC) were modified
> out of a total of over 200,000 lines of code in Berkeley DB."
Tracking the read sets of each transaction would be very expensive.
Worse still, that information needs to be kept around after
end-of-transaction, which raises questions about where it should be
stored and how it should be cleaned up. Note that the benchmarks in
the paper involve transactions that perform "a small number of simple
read and update operations", which reduces the bookkeeping overhead.
Neil
[1] http://everythingisdata.wordpress.com/2009/02/25/february-25-2009/