@ -104,20 +104,28 @@ gistbeginscan(PG_FUNCTION_ARGS)
int nkeys = PG_GETARG_INT32 ( 1 ) ;
int norderbys = PG_GETARG_INT32 ( 2 ) ;
IndexScanDesc scan ;
GISTSTATE * giststate ;
GISTScanOpaque so ;
MemoryContext oldCxt ;
scan = RelationGetIndexScan ( r , nkeys , norderbys ) ;
/* First, set up a GISTSTATE with a scan-lifespan memory context */
giststate = initGISTstate ( scan - > indexRelation ) ;
/*
* Everything made below is in the scanCxt , or is a child of the scanCxt ,
* so it ' ll all go away automatically in gistendscan .
*/
oldCxt = MemoryContextSwitchTo ( giststate - > scanCxt ) ;
/* initialize opaque data */
so = ( GISTScanOpaque ) palloc0 ( sizeof ( GISTScanOpaqueData ) ) ;
so - > queueCxt = AllocSetContextCreate ( CurrentMemoryContext ,
" GiST queue context " ,
ALLOCSET_DEFAULT_MINSIZE ,
ALLOCSET_DEFAULT_INITSIZE ,
ALLOCSET_DEFAULT_MAXSIZE ) ;
so - > tempCxt = createTempGistContext ( ) ;
so - > giststate = ( GISTSTATE * ) palloc ( sizeof ( GISTSTATE ) ) ;
initGISTstate ( so - > giststate , scan - > indexRelation ) ;
so - > giststate = giststate ;
giststate - > tempCxt = createTempGistContext ( ) ;
so - > queue = NULL ;
so - > queueCxt = giststate - > scanCxt ; /* see gistrescan */
/* workspaces with size dependent on numberOfOrderBys: */
so - > tmpTreeItem = palloc ( GSTIHDRSZ + sizeof ( double ) * scan - > numberOfOrderBys ) ;
so - > distances = palloc ( sizeof ( double ) * scan - > numberOfOrderBys ) ;
@ -125,6 +133,8 @@ gistbeginscan(PG_FUNCTION_ARGS)
scan - > opaque = so ;
MemoryContextSwitchTo ( oldCxt ) ;
PG_RETURN_POINTER ( scan ) ;
}
@ -137,12 +147,44 @@ gistrescan(PG_FUNCTION_ARGS)
/* nkeys and norderbys arguments are ignored */
GISTScanOpaque so = ( GISTScanOpaque ) scan - > opaque ;
bool first_time ;
int i ;
MemoryContext oldCxt ;
/* rescan an existing indexscan --- reset state */
MemoryContextReset ( so - > queueCxt ) ;
so - > curTreeItem = NULL ;
/*
* The first time through , we create the search queue in the scanCxt .
* Subsequent times through , we create the queue in a separate queueCxt ,
* which is created on the second call and reset on later calls . Thus , in
* the common case where a scan is only rescan ' d once , we just put the
* queue in scanCxt and don ' t pay the overhead of making a second memory
* context . If we do rescan more than once , the first RBTree is just left
* for dead until end of scan ; this small wastage seems worth the savings
* in the common case .
*/
if ( so - > queue = = NULL )
{
/* first time through */
Assert ( so - > queueCxt = = so - > giststate - > scanCxt ) ;
first_time = true ;
}
else if ( so - > queueCxt = = so - > giststate - > scanCxt )
{
/* second time through */
so - > queueCxt = AllocSetContextCreate ( so - > giststate - > scanCxt ,
" GiST queue context " ,
ALLOCSET_DEFAULT_MINSIZE ,
ALLOCSET_DEFAULT_INITSIZE ,
ALLOCSET_DEFAULT_MAXSIZE ) ;
first_time = false ;
}
else
{
/* third or later time through */
MemoryContextReset ( so - > queueCxt ) ;
first_time = false ;
}
/* create new, empty RBTree for search queue */
oldCxt = MemoryContextSwitchTo ( so - > queueCxt ) ;
@ -154,11 +196,28 @@ gistrescan(PG_FUNCTION_ARGS)
scan ) ;
MemoryContextSwitchTo ( oldCxt ) ;
so - > curTreeItem = NULL ;
so - > firstCall = true ;
/* Update scan key, if a new one is given */
if ( key & & scan - > numberOfKeys > 0 )
{
/*
* If this isn ' t the first time through , preserve the fn_extra
* pointers , so that if the consistentFns are using them to cache
* data , that data is not leaked across a rescan .
*/
if ( ! first_time )
{
for ( i = 0 ; i < scan - > numberOfKeys ; i + + )
{
ScanKey skey = scan - > keyData + i ;
so - > giststate - > consistentFn [ skey - > sk_attno - 1 ] . fn_extra =
skey - > sk_func . fn_extra ;
}
}
memmove ( scan - > keyData , key ,
scan - > numberOfKeys * sizeof ( ScanKeyData ) ) ;
@ -172,6 +231,10 @@ gistrescan(PG_FUNCTION_ARGS)
* Next , if any of keys is a NULL and that key is not marked with
* SK_SEARCHNULL / SK_SEARCHNOTNULL then nothing can be found ( ie , we
* assume all indexable operators are strict ) .
*
* Note : we intentionally memcpy the FmgrInfo to sk_func rather than
* using fmgr_info_copy . This is so that the fn_extra field gets
* preserved across multiple rescans .
*/
so - > qual_ok = true ;
@ -192,6 +255,18 @@ gistrescan(PG_FUNCTION_ARGS)
/* Update order-by key, if a new one is given */
if ( orderbys & & scan - > numberOfOrderBys > 0 )
{
/* As above, preserve fn_extra if not first time through */
if ( ! first_time )
{
for ( i = 0 ; i < scan - > numberOfOrderBys ; i + + )
{
ScanKey skey = scan - > orderByData + i ;
so - > giststate - > distanceFn [ skey - > sk_attno - 1 ] . fn_extra =
skey - > sk_func . fn_extra ;
}
}
memmove ( scan - > orderByData , orderbys ,
scan - > numberOfOrderBys * sizeof ( ScanKeyData ) ) ;
@ -201,6 +276,8 @@ gistrescan(PG_FUNCTION_ARGS)
* function in the form of its strategy number , which is available
* from the sk_strategy field , and its subtype from the sk_subtype
* field .
*
* See above comment about why we don ' t use fmgr_info_copy here .
*/
for ( i = 0 ; i < scan - > numberOfOrderBys ; i + + )
{
@ -239,13 +316,11 @@ gistendscan(PG_FUNCTION_ARGS)
IndexScanDesc scan = ( IndexScanDesc ) PG_GETARG_POINTER ( 0 ) ;
GISTScanOpaque so = ( GISTScanOpaque ) scan - > opaque ;
/*
* freeGISTstate is enough to clean up everything made by gistbeginscan ,
* as well as the queueCxt if there is a separate context for it .
*/
freeGISTstate ( so - > giststate ) ;
pfree ( so - > giststate ) ;
MemoryContextDelete ( so - > queueCxt ) ;
MemoryContextDelete ( so - > tempCxt ) ;
pfree ( so - > tmpTreeItem ) ;
pfree ( so - > distances ) ;
pfree ( so ) ;
PG_RETURN_VOID ( ) ;
}
Tom Lane
14 years ago