On 4/4/25 01:43, Tomas Vondra wrote: > On 4/4/25 00:57, David Rowley wrote: >> On Thu, 3 Apr 2025 at 04:16, Tomas Vondra <tomas.von...@postgresql.org> >> wrote: >>> Improve accounting for memory used by shared hash tables >> >> I've not looked into why, but this is causing an issue in the >> join_rel_hash during add_join_rel(). See the attached script. >> >> ERROR: pfree called with invalid pointer 0x60a15edc44e0 (header >> 0x0000002000000008) >> > > Thanks for the report and reproducer. I'll take a look tomorrow. >
I took a quick look, and I think the reason is fairly simple - the commit allocates the header and the directory as a single chunk. And for shared hash tables that's fine, because those have non-expandable directory. But the patch does the same thing for non-shared hash tables (not intentionally), which means that if we end up expanding the hash, it fails in dir_realloc(). Because hashp->dir is not a separately allocated chunk. This is clearly a bug in the patch, I should have caught this during a review. But I'm also quite surprised none of the regression tests seems to expand the hash table ... I'll think about a way to fix this tomorrow. -- Tomas Vondra
