On 28 October 2014 14:22, Simon Riggs <simon@2ndquadrant.com> wrote:
> Or put it another way, it will be easier to write new index AMs
> because we'll be able to skip the WAL part until we know we want it.
To be clear: I am suggesting you do *less* work, not more.
By allowing AMs to avoid writing WAL we get
* higher performance unlogged indexes
* we get fewer bugs in early days of new AMs
* writers of new AMs are OK to avoid majority of hard work and hard testing
So overall, we get new AMs working faster because we can skip writing
the WAL code until we are certain the new AM code is useful and bug
free.
For example, if GIN had avoided implementing WAL it would have been
easier to change on-disk representation.
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services