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Previous change exposed some opportunities for further simplification 

in _bt_first().
This commit is contained in:
Tom Lane 2003-12-21 03:00:04 +00:00
parent 569659ae16
commit 2a0caefeb5
1 changed files with 11 additions and 37 deletions
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48
src/backend/access/nbtree/nbtsearch.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * 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; BlockNumber blkno;
StrategyNumber strat; StrategyNumber strat;
bool res; bool res;
int32 result;
bool nextkey; bool nextkey;
bool continuescan; bool continuescan;
ScanKey scankeys = NULL; ScanKey scankeys;
ScanKey *startKeys = NULL; ScanKey *startKeys = NULL;
int keysCount = 0; int keysCount = 0;
int i; int i;
@ -695,8 +694,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
pfree(startKeys); pfree(startKeys);
current = &(scan->currentItemData);
/* /*
* We want to locate either the first item >= boundary point, or * We want to locate either the first item >= boundary point, or
* first item > boundary point, depending on the initial-positioning * 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... */ /* don't need to keep the stack around... */
_bt_freestack(stack); _bt_freestack(stack);
current = &(scan->currentItemData);
if (!BufferIsValid(buf)) if (!BufferIsValid(buf))
{ {
/* Only get here if index is completely empty */ /* Only get here if index is completely empty */
@ -765,6 +764,9 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
ItemPointerSet(current, blkno, offnum); ItemPointerSet(current, blkno, offnum);
/* done with manufactured scankey, now */
pfree(scankeys);
/* /*
* It's now time to examine the initial-positioning strategy to find the * It's now time to examine the initial-positioning strategy to find the
* exact place to start the scan. * exact place to start the scan.
@ -802,10 +804,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
* that is always the correct starting position.) * that is always the correct starting position.)
*/ */
if (!_bt_step(scan, &buf, BackwardScanDirection)) if (!_bt_step(scan, &buf, BackwardScanDirection))
{
pfree(scankeys);
return false; return false;
}
break; break;
case BTLessEqualStrategyNumber: case BTLessEqualStrategyNumber:
@ -818,10 +817,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
* that is always the correct starting position.) * that is always the correct starting position.)
*/ */
if (!_bt_step(scan, &buf, BackwardScanDirection)) if (!_bt_step(scan, &buf, BackwardScanDirection))
{
pfree(scankeys);
return false; return false;
}
break; break;
case BTEqualStrategyNumber: case BTEqualStrategyNumber:
@ -834,14 +830,11 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
/* /*
* We are on first item > scankey. * We are on first item > scankey.
* *
* Back up one to arrive at last item <= scankey, then * Back up one to arrive at last item <= scankey.
* check to see if it is equal to scankey. * We will check below to see if it is equal to scankey.
*/ */
if (!_bt_step(scan, &buf, BackwardScanDirection)) if (!_bt_step(scan, &buf, BackwardScanDirection))
{
pfree(scankeys);
return false; return false;
}
} }
else else
{ {
@ -849,25 +842,15 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
* We are on first item >= scankey. * We are on first item >= scankey.
* *
* Make sure we are on a real item; might have to * Make sure we are on a real item; might have to
* step forward if currently at end of page. Then check * step forward if currently at end of page.
* to see if it is equal to scankey. * We will check below to see if it is equal to scankey.
*/ */
if (offnum > PageGetMaxOffsetNumber(page)) if (offnum > PageGetMaxOffsetNumber(page))
{ {
if (!_bt_step(scan, &buf, ForwardScanDirection)) if (!_bt_step(scan, &buf, ForwardScanDirection))
{
pfree(scankeys);
return false; 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; break;
case BTGreaterEqualStrategyNumber: case BTGreaterEqualStrategyNumber:
@ -879,10 +862,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
if (offnum > PageGetMaxOffsetNumber(page)) if (offnum > PageGetMaxOffsetNumber(page))
{ {
if (!_bt_step(scan, &buf, ForwardScanDirection)) if (!_bt_step(scan, &buf, ForwardScanDirection))
{
pfree(scankeys);
return false; return false;
}
} }
break; break;
@ -895,10 +875,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
if (offnum > PageGetMaxOffsetNumber(page)) if (offnum > PageGetMaxOffsetNumber(page))
{ {
if (!_bt_step(scan, &buf, ForwardScanDirection)) if (!_bt_step(scan, &buf, ForwardScanDirection))
{
pfree(scankeys);
return false; return false;
}
} }
break; break;
} }
@ -924,15 +901,12 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
else else
{ {
/* no tuples in the index match this scan key */ /* no tuples in the index match this scan key */
nomatches:
ItemPointerSetInvalid(current); ItemPointerSetInvalid(current);
so->btso_curbuf = InvalidBuffer; so->btso_curbuf = InvalidBuffer;
_bt_relbuf(rel, buf); _bt_relbuf(rel, buf);
res = false; res = false;
} }
pfree(scankeys);
return res; return res;
} }