Rearrange heap_beginscan to eliminate extra call on

mdnblocks.  Bad enough it does an lseek, but to do it twice for no
reason...

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 89956260cee3eb6a502d224d0c486b2e73eda10a..f30b1026b82aed8eee0b09e236c6785905a64b25 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.56 1999/10/11 06:28:27 inoue Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.57 1999/10/30 23:10:21 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -102,7 +102,16 @@ initscan(HeapScanDesc scan,
                 unsigned nkeys,
                 ScanKey key)
 {
-       if (!RelationGetNumberOfBlocks(relation))
+       /* ----------------
+        *      Make sure we have up-to-date idea of number of blocks in relation.
+        *      It is sufficient to do this once at scan start, since any tuples
+        *      added while the scan is in progress will be invisible to my
+        *      transaction anyway...
+        * ----------------
+        */
+       relation->rd_nblocks = RelationGetNumberOfBlocks(relation);
+
+       if (relation->rd_nblocks == 0)
        {
                /* ----------------
                 *      relation is empty
@@ -652,11 +661,12 @@ heap_beginscan(Relation relation,
         */
        scan = (HeapScanDesc) palloc(sizeof(HeapScanDescData));
 
-       relation->rd_nblocks = smgrnblocks(DEFAULT_SMGR, relation);
        scan->rs_rd = relation;
+       scan->rs_atend = atend;
+       scan->rs_snapshot = snapshot;
+       scan->rs_nkeys = (short) nkeys;
 
        if (nkeys)
-
                /*
                 * we do this here instead of in initscan() because heap_rescan
                 * also calls initscan() and we don't want to allocate memory
@@ -668,10 +678,6 @@ heap_beginscan(Relation relation,
 
        initscan(scan, relation, atend, nkeys, key);
 
-       scan->rs_atend = atend;
-       scan->rs_snapshot = snapshot;
-       scan->rs_nkeys = (short) nkeys;
-
        return scan;
 }
 
@@ -703,8 +709,8 @@ heap_rescan(HeapScanDesc scan,
         *      reinitialize scan descriptor
         * ----------------
         */
-       initscan(scan, scan->rs_rd, scanFromEnd, scan->rs_nkeys, key);
        scan->rs_atend = (bool) scanFromEnd;
+       initscan(scan, scan->rs_rd, scanFromEnd, scan->rs_nkeys, key);
 }
 
 /* ----------------
@@ -1096,7 +1102,7 @@ heap_get_latest_tid(Relation relation,
                   Snapshot snapshot,
                   ItemPointer tid)
 {
-       ItemId          lp;
+       ItemId          lp = NULL;
        Buffer          buffer;
        PageHeader      dp;
        OffsetNumber    offnum;