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 8c26a074a7bbcda4d33c603f654e1c6f31f89d29..0e59974b0afed1edfcebf1e67ba89885ba915dd7 100644 (file)
--- 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 1.5.2.7 2007/01/14 20:18:30 alvherre Exp $
+ *       $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.5.2.8 2008/01/17 23:47:07 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -814,6 +814,10 @@ 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)
        {
@@ -827,9 +831,9 @@ test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
                anl_base_thresh = (avForm->anl_base_thresh >= 0) ?
                        avForm->anl_base_thresh : autovacuum_anl_thresh;
 
-               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) ?
@@ -845,7 +849,7 @@ test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
                anl_scale_factor = autovacuum_anl_scale;
                anl_base_thresh = autovacuum_anl_thresh;
 
-               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) ?