Previous change exposed some opportunities for further simplification

in _bt_first().

diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index 554959fc79ef8fd67809087302fe3d3d4d5256ed..cc852984ce28f69ce83e4af3c7333bc8fa6c0154 100644 (file)
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.84 2003/12/21 01:23:06 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.85 2003/12/21 03:00:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -495,10 +495,9 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
    BlockNumber blkno;
    StrategyNumber strat;
    bool        res;
-   int32       result;
    bool        nextkey;
    bool        continuescan;
-   ScanKey     scankeys = NULL;
+   ScanKey     scankeys;
    ScanKey    *startKeys = NULL;
    int         keysCount = 0;
    int         i;
@@ -695,8 +694,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
 
    pfree(startKeys);
 
-   current = &(scan->currentItemData);
-
    /*
     * We want to locate either the first item >= boundary point, or
     * first item > boundary point, depending on the initial-positioning
@@ -746,6 +743,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
    /* don't need to keep the stack around... */
    _bt_freestack(stack);
 
+   current = &(scan->currentItemData);
+
    if (!BufferIsValid(buf))
    {
        /* Only get here if index is completely empty */
@@ -765,6 +764,9 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
 
    ItemPointerSet(current, blkno, offnum);
 
+   /* done with manufactured scankey, now */
+   pfree(scankeys);
+
    /*
     * It's now time to examine the initial-positioning strategy to find the
     * exact place to start the scan.
@@ -802,10 +804,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
             * that is always the correct starting position.)
             */
            if (!_bt_step(scan, &buf, BackwardScanDirection))
-           {
-               pfree(scankeys);
                return false;
-           }
            break;
 
        case BTLessEqualStrategyNumber:
@@ -818,10 +817,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
             * that is always the correct starting position.)
             */
            if (!_bt_step(scan, &buf, BackwardScanDirection))
-           {
-               pfree(scankeys);
                return false;
-           }
            break;
 
        case BTEqualStrategyNumber:
@@ -834,14 +830,11 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
                /*
                 * We are on first item > scankey.
                 *
-                * Back up one to arrive at last item <= scankey, then
-                * check to see if it is equal to scankey.
+                * Back up one to arrive at last item <= scankey.
+                * We will check below to see if it is equal to scankey.
                 */
                if (!_bt_step(scan, &buf, BackwardScanDirection))
-               {
-                   pfree(scankeys);
                    return false;
-               }
            }
            else
            {
@@ -849,25 +842,15 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
                 * We are on first item >= scankey.
                 *
                 * Make sure we are on a real item; might have to
-                * step forward if currently at end of page.  Then check
-                * to see if it is equal to scankey.
+                * step forward if currently at end of page.
+                * We will check below to see if it is equal to scankey.
                 */
                if (offnum > PageGetMaxOffsetNumber(page))
                {
                    if (!_bt_step(scan, &buf, ForwardScanDirection))
-                   {
-                       pfree(scankeys);
                        return false;
-                   }
                }
            }
-
-           /* If we are not now on an equal item, then there ain't any. */
-           offnum = ItemPointerGetOffsetNumber(current);
-           page = BufferGetPage(buf);
-           result = _bt_compare(rel, keysCount, scankeys, page, offnum);
-           if (result != 0)
-               goto nomatches; /* no equal items! */
            break;
 
        case BTGreaterEqualStrategyNumber:
@@ -879,10 +862,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
            if (offnum > PageGetMaxOffsetNumber(page))
            {
                if (!_bt_step(scan, &buf, ForwardScanDirection))
-               {
-                   pfree(scankeys);
                    return false;
-               }
            }
            break;
 
@@ -895,10 +875,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
            if (offnum > PageGetMaxOffsetNumber(page))
            {
                if (!_bt_step(scan, &buf, ForwardScanDirection))
-               {
-                   pfree(scankeys);
                    return false;
-               }
            }
            break;
    }
@@ -924,15 +901,12 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
    else
    {
        /* no tuples in the index match this scan key */
-nomatches:
        ItemPointerSetInvalid(current);
        so->btso_curbuf = InvalidBuffer;
        _bt_relbuf(rel, buf);
        res = false;
    }
 
-   pfree(scankeys);
-
    return res;
 }