On Thu, Dec 6, 2018 at 12:51 PM Alexander Korotkov <aekorot...@gmail.com> wrote: > So, algorithm introduced by 218f51584d5 is broken. It tries to > guarantee that there are no inserters in the subtree by placing > cleanup lock to subtree root, assuming that inserter holds pins on the > path from root to leaf. But due to concurrent splits of internal > pages the pins held can be not relevant to actual path. I don't see > the way to fix this easily. So, I think we should revert it from back > branches and try to reimplement that in master. > > However, I'd like to note that 218f51584d5 introduces two changes: > 1) Cleanup locking only if there pages to delete > 2) Cleanup locking only subtree root > The 2nd one is broken. But the 1st one seems still good for me and > useful, because in vast majority of cases vacuum doesn't delete any > index pages. So, I propose to revert 218f51584d5, but leave there > logic, which locks root for cleanup only once there are pages to > delete. Any thoughts?
Can you post a patch that just removes the 2nd part, leaving the still-correct first part? Your proposal sounds reasonable, but I'd like to see what you have in mind in detail before commenting. Thanks -- Peter Geoghegan
