Deduplicate PageIsNew() check in lazy_scan_heap().

The recheck isn't needed anymore, as RelationGetBufferForTuple() now
extends the relation with RBM_ZERO_AND_LOCK. Previously we needed to
handle the fact that relation extension extended the relation and then
separately acquired a lock on the page - while expecting that the page
is empty.

Reported-By: Ranier Vilela
Discussion: https://postgr.es/m/CAEudQArA_=J0D5T258xsCY6Xtf6wiH4b=QDPDgVS+WZUN10WDw@mail.gmail.com

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 9726f696298dab7c4d9346fb519fdec1a0262e22..edda82abd0158a9d77731277e2b4d29ea1af2fa0 100644 (file)
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -1147,8 +1147,6 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
        if (PageIsNew(page))
        {
-           bool        still_new;
-
            /*
             * All-zeroes pages can be left over if either a backend extends
             * the relation by a single page, but crashes before the newly
@@ -1156,36 +1154,28 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
             * the relation (which creates a number of empty pages at the tail
             * end of the relation, but enters them into the FSM).
             *
-            * Make sure these pages are in the FSM, to ensure they can be
-            * reused. Do that by testing if there's any space recorded for
-            * the page. If not, enter it.
-            *
             * Note we do not enter the page into the visibilitymap. That has
             * the downside that we repeatedly visit this page in subsequent
             * vacuums, but otherwise we'll never not discover the space on a
             * promoted standby. The harm of repeated checking ought to
             * normally not be too bad - the space usually should be used at
             * some point, otherwise there wouldn't be any regular vacuums.
+            *
+            * Make sure these pages are in the FSM, to ensure they can be
+            * reused. Do that by testing if there's any space recorded for
+            * the page. If not, enter it. We do so after releasing the lock
+            * on the heap page, the FSM is approximate, after all.
             */
-
-           /*
-            * Perform checking of FSM after releasing lock, the fsm is
-            * approximate, after all.
-            */
-           still_new = PageIsNew(page);
            UnlockReleaseBuffer(buf);
 
-           if (still_new)
-           {
-               empty_pages++;
+           empty_pages++;
 
-               if (GetRecordedFreeSpace(onerel, blkno) == 0)
-               {
-                   Size        freespace;
+           if (GetRecordedFreeSpace(onerel, blkno) == 0)
+           {
+               Size        freespace;
 
-                   freespace = BufferGetPageSize(buf) - SizeOfPageHeaderData;
-                   RecordPageWithFreeSpace(onerel, blkno, freespace);
-               }
+               freespace = BufferGetPageSize(buf) - SizeOfPageHeaderData;
+               RecordPageWithFreeSpace(onerel, blkno, freespace);
            }
            continue;
        }