@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $ PostgreSQL : pgsql / src / backend / access / hash / hashsearch . c , v 1.53 2008 / 06 / 19 00 : 46 : 03 alvherre Exp $
* $ PostgreSQL : pgsql / src / backend / access / hash / hashsearch . c , v 1.54 2008 / 09 / 15 18 : 43 : 41 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -178,6 +178,8 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
hashkey = _hash_datum2hashkey_type ( rel , cur - > sk_argument ,
cur - > sk_subtype ) ;
so - > hashso_sk_hash = hashkey ;
/*
* Acquire shared split lock so we can compute the target bucket safely
* ( see README ) .
@ -186,7 +188,7 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
/* Read the metapage */
metabuf = _hash_getbuf ( rel , HASH_METAPAGE , HASH_READ , LH_META_PAGE ) ;
metap = ( HashMetaPage ) BufferGetPage ( metabuf ) ;
metap = HashPageGetMeta ( BufferGetPage ( metabuf ) ) ;
/*
* Compute the target bucket number , and convert to block number .
@ -284,7 +286,7 @@ _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
offnum = InvalidOffsetNumber ;
/*
* ' offnum ' now points to the last tuple we have seen ( if any ) .
* ' offnum ' now points to the last tuple we examined ( if any ) .
*
* continue to step through tuples until : 1 ) we get to the end of the
* bucket chain or 2 ) we find a valid tuple .
@ -297,25 +299,39 @@ _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
if ( offnum ! = InvalidOffsetNumber )
offnum = OffsetNumberNext ( offnum ) ; /* move forward */
else
offnum = FirstOffsetNumber ; /* new page */
{
/* new page, locate starting position by binary search */
offnum = _hash_binsearch ( page , so - > hashso_sk_hash ) ;
}
while ( offnum > maxoff )
for ( ; ; )
{
/*
* either this page is empty ( maxoff = =
* InvalidOffsetNumber ) or we ran off the end .
* check if we ' re still in the range of items with
* the target hash key
*/
if ( offnum < = maxoff )
{
Assert ( offnum > = FirstOffsetNumber ) ;
itup = ( IndexTuple ) PageGetItem ( page , PageGetItemId ( page , offnum ) ) ;
if ( so - > hashso_sk_hash = = _hash_get_indextuple_hashkey ( itup ) )
break ; /* yes, so exit for-loop */
}
/*
* ran off the end of this page , try the next
*/
_hash_readnext ( rel , & buf , & page , & opaque ) ;
if ( BufferIsValid ( buf ) )
{
maxoff = PageGetMaxOffsetNumber ( page ) ;
offnum = FirstOffsetNumber ;
offnum = _hash_binsearch ( page , so - > hashso_sk_hash ) ;
}
else
{
/* end of bucket */
maxoff = offnum = InvalidOffsetNumber ;
break ; /* exit while */
itup = NULL ;
break ; /* exit for-loop */
}
}
break ;
@ -324,22 +340,39 @@ _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
if ( offnum ! = InvalidOffsetNumber )
offnum = OffsetNumberPrev ( offnum ) ; /* move back */
else
offnum = maxoff ; /* new page */
{
/* new page, locate starting position by binary search */
offnum = _hash_binsearch_last ( page , so - > hashso_sk_hash ) ;
}
while ( offnum < FirstOffsetNumber )
for ( ; ; )
{
/*
* either this page is empty ( offnum = =
* InvalidOffsetNumber ) or we ran off the end .
* check if we ' re still in the range of items with
* the target hash key
*/
if ( offnum > = FirstOffsetNumber )
{
Assert ( offnum < = maxoff ) ;
itup = ( IndexTuple ) PageGetItem ( page , PageGetItemId ( page , offnum ) ) ;
if ( so - > hashso_sk_hash = = _hash_get_indextuple_hashkey ( itup ) )
break ; /* yes, so exit for-loop */
}
/*
* ran off the end of this page , try the next
*/
_hash_readprev ( rel , & buf , & page , & opaque ) ;
if ( BufferIsValid ( buf ) )
maxoff = offnum = PageGetMaxOffsetNumber ( page ) ;
{
maxoff = PageGetMaxOffsetNumber ( page ) ;
offnum = _hash_binsearch_last ( page , so - > hashso_sk_hash ) ;
}
else
{
/* end of bucket */
maxoff = offnum = InvalidOffsetNumber ;
break ; /* exit while */
itup = NULL ;
break ; /* exit for-loop */
}
}
break ;
@ -347,19 +380,19 @@ _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
default :
/* NoMovementScanDirection */
/* this should not be reached */
itup = NULL ;
break ;
}
/* we ran off the end of the world without finding a match */
if ( offnum = = InvalidOffsetNumber )
if ( itup = = NULL )
{
/* we ran off the end of the bucket without finding a match */
* bufP = so - > hashso_curbuf = InvalidBuffer ;
ItemPointerSetInvalid ( current ) ;
return false ;
}
/* get ready to check this tuple */
itup = ( IndexTuple ) PageGetItem ( page , PageGetItemId ( page , offnum ) ) ;
/* check the tuple quals, loop around if not met */
} while ( ! _hash_checkqual ( scan , itup ) ) ;
/* if we made it to here, we've found a valid tuple */
Tom Lane
17 years ago