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1. BTREE_VERSION_1: using bti_itup->t_tid as unique identifier for a given

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index tuple (logical position within A LEVEL). bti_oid & bti_dummy
taken off from BTItemData.
2. Fix for multi-column indices (nbtsearch.c):
   _bt_binsrch() - for searches on internal pages having keysize <
	number of attrs we point at the last item < the scankey, not at the
	first item = the scankey;
   _bt_moveright() - if keysize < number of attrs we compare scankey with
	_last_ item on current page to decide should we move right or
	not.
This commit is contained in:
Vadim B. Mikheev
1997-04-16 01:48:29 +00:00
parent afd9295786
commit 329fb11262
5 changed files with 170 additions and 102 deletions
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152
src/backend/access/nbtree/nbtsearch.c
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@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.16 1997/03/24 08:48:12 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.17 1997/04/16 01:48:17 vadim Exp $
*
*-------------------------------------------------------------------------
*/
@@ -160,7 +160,8 @@ _bt_moveright(Relation rel,
ItemId hikey;
ItemId itemid;
BlockNumber rblkno;
int natts = rel->rd_rel->relnatts;
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
@@ -178,22 +179,43 @@ _bt_moveright(Relation rel,
*/
if (_bt_skeycmp(rel, keysz, scankey, page, hikey,
BTGreaterEqualStrategyNumber)) {
BTGreaterEqualStrategyNumber))
{
/* move right as long as we need to */
do {
do
{
OffsetNumber offmax;
/*
* If this page consists of all duplicate keys (hikey and first
* key on the page have the same value), then we don't need to
* step right.
*
* NOTE for multi-column indices: we may do scan using
* keys not for all attrs. But we handle duplicates
* using all attrs in _bt_insert/_bt_spool code.
* And so we've to compare scankey with _last_ item
* on this page to do not lose "good" tuples if number
* of attrs > keysize. Example: (2,0) - last items on
* this page, (2,1) - first item on next page (hikey),
* our scankey is x = 2. Scankey >= (2,1) because of
* we compare first attrs only, but we shouldn't to move
* right of here. - vadim 04/15/97
*/
if (PageGetMaxOffsetNumber(page) > P_HIKEY) {
if ( (offmax = PageGetMaxOffsetNumber(page)) > P_HIKEY)
{
itemid = PageGetItemId(page, P_FIRSTKEY);
if (_bt_skeycmp(rel, keysz, scankey, page, itemid,
BTEqualStrategyNumber)) {
/* break is for the "move right" while loop */
break;
}
else if ( natts > keysz )
{
itemid = PageGetItemId(page, offmax);
if (_bt_skeycmp(rel, keysz, scankey, page, itemid,
BTLessEqualStrategyNumber))
break;
}
}
/* step right one page */
@@ -346,6 +368,7 @@ _bt_binsrch(Relation rel,
Page page;
BTPageOpaque opaque;
OffsetNumber low, mid, high;
int natts = rel->rd_rel->relnatts;
int result;
page = BufferGetPage(buf);
@@ -379,55 +402,84 @@ _bt_binsrch(Relation rel,
else if (result < 0)
high = mid - 1;
else
return (_bt_firsteq(rel, itupdesc, page, keysz, scankey, mid));
{
mid = _bt_firsteq(rel, itupdesc, page, keysz, scankey, mid);
/*
* NOTE for multi-column indices: we may do scan using
* keys not for all attrs. But we handle duplicates using
* all attrs in _bt_insert/_bt_spool code. And so while
* searching on internal pages having number of attrs > keysize
* we want to point at the last item < the scankey, not at the
* first item = the scankey (!!!), and let _bt_moveright
* decide later whether to move right or not (see comments and
* example there). Note also that INSERTions are not affected
* by this code (natts == keysz). - vadim 04/15/97
*/
if ( natts == keysz || opaque->btpo_flags & BTP_LEAF )
return (mid);
low = P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY;
if ( mid == low )
return (mid);
return (OffsetNumberPrev(mid));
}
}
/*
* We terminated because the endpoints got too close together. There
* are two cases to take care of.
*
* For non-insertion searches on internal pages, we want to point at
* the last key <, or first key =, the scankey on the page. This
* guarantees that we'll descend the tree correctly.
*
* For all other cases, we want to point at the first key >=
* the scankey on the page. This guarantees that scans and
* insertions will happen correctly.
*/
/*
* We terminated because the endpoints got too close together. There
* are two cases to take care of.
*
* For non-insertion searches on internal pages, we want to point at
* the last key <, or first key =, the scankey on the page. This
* guarantees that we'll descend the tree correctly.
* (NOTE comments above for multi-column indices).
*
* For all other cases, we want to point at the first key >=
* the scankey on the page. This guarantees that scans and
* insertions will happen correctly.
*/
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (!(opaque->btpo_flags & BTP_LEAF) && srchtype == BT_DESCENT) {
if (!(opaque->btpo_flags & BTP_LEAF) && srchtype == BT_DESCENT)
{ /*
* We want the last key <, or first key ==, the scan key.
*/
result = _bt_compare(rel, itupdesc, page, keysz, scankey, high);
if (result == 0)
{
mid = _bt_firsteq(rel, itupdesc, page, keysz, scankey, high);
/*
* We want the last key <, or first key ==, the scan key.
* If natts > keysz we want last item < the scan key.
* See comments above for multi-column indices.
*/
result = _bt_compare(rel, itupdesc, page, keysz, scankey, high);
if (result == 0) {
return (_bt_firsteq(rel, itupdesc, page, keysz, scankey, high));
} else if (result > 0) {
return (high);
} else {
return (low);
}
} else {
/* we want the first key >= the scan key */
result = _bt_compare(rel, itupdesc, page, keysz, scankey, low);
if (result <= 0) {
return (low);
} else {
if (low == high)
return (OffsetNumberNext(low));
result = _bt_compare(rel, itupdesc, page, keysz, scankey, high);
if (result <= 0)
return (high);
else
return (OffsetNumberNext(high));
}
if ( natts == keysz )
return (mid);
low = P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY;
if ( mid == low )
return (mid);
return (OffsetNumberPrev(mid));
}
else if (result > 0)
return (high);
else
return (low);
}
else /* we want the first key >= the scan key */
{
result = _bt_compare(rel, itupdesc, page, keysz, scankey, low);
if (result <= 0)
return (low);
else
{
if (low == high)
return (OffsetNumberNext(low));
result = _bt_compare(rel, itupdesc, page, keysz, scankey, high);
if (result <= 0)
return (high);
else
return (OffsetNumberNext(high));
}
}
}
static OffsetNumber
@@ -1107,7 +1159,7 @@ _bt_twostep(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
while (offnum <= maxoff) {
itemid = PageGetItemId(page, offnum);
btitem = (BTItem) PageGetItem(page, itemid);
if (btitem->bti_oid == svitem->bti_oid) {
if ( BTItemSame (btitem, svitem) ) {
pfree(svitem);
ItemPointerSet(current, blkno, offnum);
return (false);