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;