On 3 August 2015 at 17:18, Jeff Janes <jeff.ja...@gmail.com> wrote:
> That does still leave the prefetch technique, so all is not lost. >> >> Can we see a patch with just prefetch, probably with a simple choice of >> stride? Thanks. >> > > I probably won't get back to it this commit fest, so it can be set to > returned with feedback. But if anyone has good ideas for how to set the > stride (or detect that it is on SSD and so is pointless to try) I'd love to > hear about them anytime. > I've Returned With Feedback, as you suggest. Given your earlier numbers, I'd just pick a constant value of 128, to keep it simple. That balances out the various factors of small/large tables and the uncertainty that we will be able to truncate the whole chunk of blocks. I'd like to see tests on SSD before commit, but I hope and expect the slightly negative results with SSD won't be substantiated on larger tests. Kept simple, its a patch with a clear win in a restricted use case and I would be happy to commit that sometime in the future. -- Simon Riggs http://www.2ndQuadrant.com/ <http://www.2ndquadrant.com/> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
