Re: Serializable Isolation without blocking

Hi,

Kevin Grittner wrote:
> I had this flagged as needing a response, but it fell through the
> cracks yesterday. Apologies for the delayed response.

No problem.

> Markus Wanner <markus(at)bluegap(dot)ch> wrote:
> When the Cahill paper talks about predicate locking, it *is* talking
> about what to lock with SIREAD locks, at least as I read it. If you
> see something to indicate otherwise, please share. (If I'm off base
> on understanding any of this, I'd sure like to get straightened out
> as soon as possible.)

I don't remember reading about predicate locking in the paper I read.
Either he didn't cover that in his first implementation (based on page
level locking), or I've simply re-used that part of my in-brain-memory.

> It was the way Sybase worked for ages, too. If you consider that
> you're locking both the heap and index pages read, it becomes clear
> that in order to add a row which conflicts with a predicate, you
> have to modify a page which would have been read to check the
> predicate.

Hm.. interesting, thanks for this quick explanation.

>> How about storing the SIREAD info in shared memory and using
>> dynamic granularity based on the conflict rate and available
>> memory? *duck*
>
> Don't duck. That's the plan. I really wish I was better at
> communicating these things. :-( See lock.c and the associated
> README and see if you don't think they would fit the bill.

Cool!

> Exactly. That's the plan. Implement it in the simplest form, then
> optimize.

Perfect!

Regards

Markus Wanner