@ -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 .
*/
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 ) ;
opaque = ( BTPageOpaque ) PageGetSpecialPointer ( page ) ;
if ( ! ( opaque - > btpo_flags & BTP_LEAF ) & & srchtype = = BT_DESCENT ) {
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 .
*/
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 ( _bt_firsteq ( rel , itupdesc , page , keysz , scankey , high ) ) ;
} else if ( result > 0 ) {
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 ) ) ;
}
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 ) ;
Vadim B. Mikheev
29 years ago