From 834ec73bad5967b99a1ab2497d02b4af532567bf Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Fri, 24 Jul 2026 14:33:58 +0200 Subject: [PATCH v2 1/2] Initialize bs_reltuples field in GIN parallel builds In parallel GIN builds, each worker reports the number of processed table rows and reports it to the leader, who then stores the total as thhe table's pg_class.reltuples. But gin_parallel_build_main failed to initialize the bs_reltuples field of the worker's GinBuildState, before accumulating the number of scanned tuples into it. The initial value is therefore whatever was on the stack, and it may be set to values like Infinity, NaN or extremely high value. That means the total stored in pg_class.reltuples may be arbitrary too. This can have serious consequences. The pg_class.reltuples value is used to decide when a table is due for autovacuum or autoanalyze, and if it happens to such bogus value, that may never happen. The value is also used by query optimizer when calculating various costs. Fixed by properly initializing bs_reltuples together with the rest of the build state. The bs_numtuples was initialized later, but it seems cleaner to just initialize all the fields at once. Backpatch to 18, where parallel GIN builds were introduced. Reported-by: Jan Nidzwetzki Discussion: https://postgr.es/m/518BA772-8026-412A-AA8F-A7FE4C6B3717@planetscale.com Backpatch-through: 18 --- src/backend/access/gin/gininsert.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c index cb9ed3b563c..16abb76c001 100644 --- a/src/backend/access/gin/gininsert.c +++ b/src/backend/access/gin/gininsert.c @@ -1875,9 +1875,6 @@ _gin_process_worker_data(GinBuildState *state, Tuplesortstate *worker_sort, tuplesort_performsort(state->bs_worker_sort); - /* reset the number of GIN tuples produced by this worker */ - state->bs_numtuples = 0; - if (progress) pgstat_progress_update_param(PROGRESS_CREATEIDX_SUBPHASE, PROGRESS_GIN_PHASE_MERGE_1); @@ -2158,6 +2155,11 @@ _gin_parallel_build_main(dsm_segment *seg, shm_toc *toc) /* initialize the GIN build state */ initGinState(&buildstate.ginstate, indexRel); buildstate.indtuples = 0; + + /* Initialize counters used to report tuple counts to the leader */ + buildstate.bs_numtuples = 0; + buildstate.bs_reltuples = 0; + memset(&buildstate.buildStats, 0, sizeof(GinStatsData)); memset(&buildstate.tid, 0, sizeof(ItemPointerData)); -- 2.55.0