VACUUM VERBOSE: Show dead items for an empty table.

Be consistent about the lines that VACUUM VERBOSE outputs by including
an "index scan not needed: " line for completely empty tables. This
makes the output more readable, especially with multiple distinct VACUUM
operations processed by the same VACUUM command.  It's also more
consistent; even empty tables can use the failsafe, which wasn't
reported in the standard way until now.

Follow-up to commit 6e20f460, which taught VACUUM VERBOSE to be more
consistent about reporting on scanned pages with empty tables.

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 3259ebd98a41c8fb83950df943dd2753a54a828e..8abb6dca419aa94c2c419e6ed9c163579f9677fa 100644 (file)
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -715,31 +715,29 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
                                 _("new relminmxid: %u, which is %d MXIDs ahead of previous value\n"),
                                 vacrel->NewRelminMxid, diff);
            }
-           if (orig_rel_pages > 0)
+           if (vacrel->do_index_vacuuming)
            {
-               if (vacrel->do_index_vacuuming)
-               {
-                   if (vacrel->nindexes == 0 || vacrel->num_index_scans == 0)
-                       appendStringInfoString(&buf, _("index scan not needed: "));
-                   else
-                       appendStringInfoString(&buf, _("index scan needed: "));
+               if (vacrel->nindexes == 0 || vacrel->num_index_scans == 0)
+                   appendStringInfoString(&buf, _("index scan not needed: "));
+               else
+                   appendStringInfoString(&buf, _("index scan needed: "));
 
-                   msgfmt = _("%u pages from table (%.2f%% of total) had %lld dead item identifiers removed\n");
-               }
+               msgfmt = _("%u pages from table (%.2f%% of total) had %lld dead item identifiers removed\n");
+           }
+           else
+           {
+               if (!vacrel->failsafe_active)
+                   appendStringInfoString(&buf, _("index scan bypassed: "));
                else
-               {
-                   if (!vacrel->failsafe_active)
-                       appendStringInfoString(&buf, _("index scan bypassed: "));
-                   else
-                       appendStringInfoString(&buf, _("index scan bypassed by failsafe: "));
+                   appendStringInfoString(&buf, _("index scan bypassed by failsafe: "));
 
-                   msgfmt = _("%u pages from table (%.2f%% of total) have %lld dead item identifiers\n");
-               }
-               appendStringInfo(&buf, msgfmt,
-                                vacrel->lpdead_item_pages,
-                                100.0 * vacrel->lpdead_item_pages / orig_rel_pages,
-                                (long long) vacrel->lpdead_items);
+               msgfmt = _("%u pages from table (%.2f%% of total) have %lld dead item identifiers\n");
            }
+           appendStringInfo(&buf, msgfmt,
+                            vacrel->lpdead_item_pages,
+                            orig_rel_pages == 0 ? 100.0 :
+                            100.0 * vacrel->lpdead_item_pages / orig_rel_pages,
+                            (long long) vacrel->lpdead_items);
            for (int i = 0; i < vacrel->nindexes; i++)
            {
                IndexBulkDeleteResult *istat = vacrel->indstats[i];