On 1 October 2014 09:44, Peter Geoghegan <pg@heroku.com> wrote:
> In the hope of unblocking things, I have created this Wiki page, which
> details the advantages and disadvantages of all 3 approaches that have
> been discussed, as suggested by myself and others:
>
> https://wiki.postgresql.org/wiki/Value_locking
A better job is needed at genuine balance on those items. You keep
saying you don't care which approach you take and then every word you
write goes against that, making it difficult to discuss.
Quoting general research and other points about value locking are
reasonable in the general section, but not in the description for 1.
I'm glad you've called the first option "Heavyweight Page Locking".
That name sums up what I see as the major objection to it, which is
that performance and scalability of the whole server will be damaged
signiciantly by using heavyweight locks for each row inserted. Please
add that concern as a negative; I'm sure testing has been done, but
not comparative testing against other techniques. I am motivated to
explain the promise index tuple approach further because of this,
which is an optimistic approach to locking.
The stated disadvantages for 3 are not accurate, to put it mildly. But
that's been useful because what was a small thought experiment is
beginning to look like a useful approach. I will post a summary of my
understanding.
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services