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 554959f..cc85298 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;
 }