Re: reducing the overhead of frequent table locks - now, with WIP patch

On Mon, Jun 6, 2011 at 3:59 PM, Christopher Browne <cbbrowne@gmail.com> wrote:
> On Mon, Jun 6, 2011 at 5:13 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> The cost to us is a few days work and the benefit is a whole year's
>> worth of increased performance for our user base, which has a hardware
>> equivalent well into the millions of dollars.
>
> I doubt that this is an accurate reflection of the cost.
>
> What was presented by Robert Haas was a "proof of concept," and he
> pointed out that it had numerous problems.  To requote:
>
> "There are numerous problems with the code as it stands at this point.
> It crashes if you try to use 2PC, which means the regression tests
> fail; it probably does horrible things if you run out of shared
> memory; pg_locks knows nothing about the new mechanism (arguably, we
> could leave it that way: only locks that can't possibly be conflicting
> with anything can be taken using this mechanism, but it would be nice
> to fix, I think); and there are likely some other gotchas as well."

The latest version of the patch is in much better shape:

http://archives.postgresql.org/pgsql-hackers/2011-06/msg00403.php

But this is not intended as disparagement for the balance of your argument.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company