On Sun, Feb 10, 2019 at 2:37 AM Thomas Munro <thomas.mu...@enterprisedb.com> wrote: > ... but why would it do that? I can reproduce cases where (for > example) FreePageManagerPutInternal() returns 179, and then > FreePageManagerLargestContiguous() returns 179, but then after > FreePageBtreeCleanup() it returns 178. At that point FreePageDump() > says: > > btree depth 1: > 77@0 l: 27(1) 78(178) > freelists: > 1: 27 > 129: 78(178) > > But at first glance it shouldn't be allocating pages, because it just > does consolidation to try to convert to singleton format, and then it > does recycle list cleanup using soft=true so that no allocation of > btree pages should occur.
I think I see what's happening. At the moment the problem occurs, there is no btree - there is only a singleton range. So FreePageManagerInternal() takes the fpm->btree_depth == 0 branch and then ends up in the section with the comment /* Not contiguous; we need to initialize the btree. */. And that section, sadly, does not respect the 'soft' flag, so kaboom. Something like the attached might fix it. Boy, I love FreePageManagerDump! -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
dsa-allocate-btree-init-soft.patch
Description: Binary data
