/*
* btgetbitmap() -- gets all matching tuples, and adds them to a bitmap
*/
Datum
btgetbitmap(PG_FUNCTION_ARGS)
{
IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
BTScanOpaque so = (BTScanOpaque) scan->opaque;
int64 ntids = 0;
ItemPointer heapTid;
/*
* If we have any array keys, initialize them.
*/
if (so->numArrayKeys)
{
/* punt if we have any unsatisfiable array keys */
if (so->numArrayKeys < 0)
PG_RETURN_INT64(ntids);
_bt_start_array_keys(scan, ForwardScanDirection);
}
/* This loop handles advancing to the next array elements, if any */
do
{
/* Fetch the first page & tuple */
if (_bt_first(scan, ForwardScanDirection))
{
/* Save tuple ID, and continue scanning */
heapTid = &scan->xs_ctup.t_self;
tbm_add_tuples(tbm, heapTid, 1, false);
ntids++;
for (;;)
{
/*
* Advance to next tuple within page. This is the same as the
* easy case in _bt_next().
*/
if (++so->currPos.itemIndex > so->currPos.lastItem)
{
/* let _bt_next do the heavy lifting */
if (!_bt_next(scan, ForwardScanDirection))
break;
}
/* Save tuple ID, and continue scanning */
heapTid = &so->currPos.items[so->currPos.itemIndex].heapTid;
tbm_add_tuples(tbm, heapTid, 1, false);
ntids++;
}
}
/* Now see if we have more array keys to deal with */
} while (so->numArrayKeys && _bt_advance_array_keys(scan, ForwardScanDirection));
PG_RETURN_INT64(ntids);
}
/*
* btgettuple() -- Get the next tuple in the scan.
*/
bool
btgettuple(IndexScanDesc scan, ScanDirection dir)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
bool res;
/* btree indexes are never lossy */
scan->xs_recheck = false;
/*
* If we have any array keys, initialize them during first call for a
* scan. We can't do this in btrescan because we don't know the scan
* direction at that time.
*/
if (so->numArrayKeys && !BTScanPosIsValid(so->currPos))
{
/* punt if we have any unsatisfiable array keys */
if (so->numArrayKeys < 0)
return false;
_bt_start_array_keys(scan, dir);
}
/* This loop handles advancing to the next array elements, if any */
do
{
/*
* If we've already initialized this scan, we can just advance it in
* the appropriate direction. If we haven't done so yet, we call
* _bt_first() to get the first item in the scan.
*/
if (!BTScanPosIsValid(so->currPos))
res = _bt_first(scan, dir);
else
{
/*
* Check to see if we should kill the previously-fetched tuple.
*/
if (scan->kill_prior_tuple)
{
/*
* Yes, remember it for later. (We'll deal with all such
* tuples at once right before leaving the index page.) The
* test for numKilled overrun is not just paranoia: if the
* caller reverses direction in the indexscan then the same
* item might get entered multiple times. It's not worth
* trying to optimize that, so we don't detect it, but instead
* just forget any excess entries.
*/
if (so->killedItems == NULL)
so->killedItems = (int *)
palloc(MaxIndexTuplesPerPage * sizeof(int));
if (so->numKilled < MaxIndexTuplesPerPage)
so->killedItems[so->numKilled++] = so->currPos.itemIndex;
}
/*
* Now continue the scan.
*/
res = _bt_next(scan, dir);
}
/* If we have a tuple, return it ... */
if (res)
break;
/* ... otherwise see if we have more array keys to deal with */
} while (so->numArrayKeys && _bt_advance_array_keys(scan, dir));
return res;
}