Dear Michael, Amit, > > Amit, this has been applied as of 861f86beea1c, and I got pinged about > the fact this triggers inconsistencies because we always set the LSN > of the write buffer (wbuf in _hash_freeovflpage) but > XLogRegisterBuffer() would *not* be called when the two following > conditions happen: > - When xlrec.ntups <= 0. > - When !xlrec.is_prim_bucket_same_wrt && !xlrec.is_prev_bucket_same_wrt > > And it seems to me that there is still a bug here: there should be no > point in setting the LSN on the write buffer if we don't register it > in WAL at all, no?
Thanks for pointing out, I agreed your saying. PSA the patch for diagnosing the issue. This patch can avoid the inconsistency due to the LSN setting and output a debug LOG when we met such a case. I executed hash_index.sql and confirmed the log was output [1]. This meant that current test has already had a workload which meets below conditions: - the overflow page has no tuples (xlrec.ntups is 0), - to-be-written page - wbuf - is not the primary (xlrec.is_prim_bucket_same_wrt is false), and - to-be-written buffer is not next to the overflow page (xlrec.is_prev_bucket_same_wrt is false) So, I think my patch (after removing elog(...) part) can fix the issue. Thought? [1]: ``` LOG: XXX: is_wbuf_registered: false CONTEXT: while vacuuming index "hash_cleanup_index" of relation "public.hash_cleanup_heap" STATEMENT: VACUUM hash_cleanup_heap; ``` Best Regards, Hayato Kuroda FUJITSU LIMITED https://www.fujitsu.com/
avoid_registration.patch
Description: avoid_registration.patch
