From a4d58727191419b89126f06f23237986cae966fc Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 8 Jun 2007 21:21:28 +0000 Subject: [PATCH] Disallow the cost balancing code from resulting in a zero cost limit, which causes a division-by-zero error in the vacuum code. This can happen when there are more workers than cost limit units. Per report from Galy Lee in <200705310914.l4V9E6JA094603@wwwmaster.postgresql.org>. --- src/backend/postmaster/autovacuum.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c index 07bf40707e..82a2bc71a0 100644 --- a/src/backend/postmaster/autovacuum.c +++ b/src/backend/postmaster/autovacuum.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.48 2007/06/08 21:09:49 alvherre Exp $ + * $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.49 2007/06/08 21:21:28 alvherre Exp $ * *------------------------------------------------------------------------- */ @@ -1599,7 +1599,11 @@ autovac_balance_cost(void) int limit = (int) (cost_avail * worker->wi_cost_limit_base / cost_total); - worker->wi_cost_limit = Min(limit, worker->wi_cost_limit_base); + /* + * We put a lower bound of 1 to the cost_limit, to avoid division- + * by-zero in the vacuum code. + */ + worker->wi_cost_limit = Max(Min(limit, worker->wi_cost_limit_base), 1); elog(DEBUG2, "autovac_balance_cost(pid=%u db=%u, rel=%u, cost_limit=%d, cost_delay=%d)", worker->wi_workerpid, worker->wi_dboid,