Backpatch my fix of rev 1.48 to avoid a division-by-zero error in the

cost-limit vacuum code.  Per trouble report from Joshua Drake.

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 9b039cfa6b92063c8bfad4394b8096aa5f13caf1..ccf6ea5c33b3962527d6913b4f758a20d5811ebf 100644 (file)
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -736,6 +736,9 @@ test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
         * If there is a tuple in pg_autovacuum, use it; else, use the GUC
         * defaults.  Note that the fields may contain "-1" (or indeed any
         * negative value), which means use the GUC defaults for each setting.
+        *
+        * Note: in cost_limit, 0 also means use the value from elsewhere,
+        * because 0 is not a valid value for VacuumCostLimit.
         */
        if (avForm != NULL)
        {
@@ -755,9 +758,9 @@ test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
                        Min(avForm->freeze_max_age, autovacuum_freeze_max_age) :
                        autovacuum_freeze_max_age;
 
-               vac_cost_limit = (avForm->vac_cost_limit >= 0) ?
+               vac_cost_limit = (avForm->vac_cost_limit > 0) ?
                        avForm->vac_cost_limit :
-                       ((autovacuum_vac_cost_limit >= 0) ?
+                       ((autovacuum_vac_cost_limit > 0) ?
                         autovacuum_vac_cost_limit : VacuumCostLimit);
 
                vac_cost_delay = (avForm->vac_cost_delay >= 0) ?
@@ -776,7 +779,7 @@ test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
                freeze_min_age = default_freeze_min_age;
                freeze_max_age = autovacuum_freeze_max_age;
 
-               vac_cost_limit = (autovacuum_vac_cost_limit >= 0) ?
+               vac_cost_limit = (autovacuum_vac_cost_limit > 0) ?
                        autovacuum_vac_cost_limit : VacuumCostLimit;
 
                vac_cost_delay = (autovacuum_vac_cost_delay >= 0) ?