/* ----------------------------------------------------------------
* ExternalNext
*
* This is a workhorse for ExecExtScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ExternalNext(ExternalScanState *node)
{
HeapTuple tuple;
FileScanDesc scandesc;
Index scanrelid;
EState *estate;
ScanDirection direction;
TupleTableSlot *slot;
/*
* get information from the estate and scan state
*/
estate = node->ss.ps.state;
scandesc = node->ess_ScanDesc;
scanrelid = ((ExternalScan *) node->ss.ps.plan)->scan.scanrelid;
direction = estate->es_direction;
slot = node->ss.ss_ScanTupleSlot;
/*
* get the next tuple from the file access methods
*/
tuple = external_getnext(scandesc, direction);
/*
* save the tuple and the buffer returned to us by the access methods in
* our scan tuple slot and return the slot. Note: we pass 'false' because
* tuples returned by heap_getnext() are pointers onto disk pages and were
* not created with palloc() and so should not be pfree()'d. Note also
* that ExecStoreTuple will increment the refcount of the buffer; the
* refcount will not be dropped until the tuple table slot is cleared.
*/
if (tuple)
{
Gpmon_M_Incr_Rows_Out(GpmonPktFromExtScanState(node));
CheckSendPlanStateGpmonPkt(&node->ss.ps);
ExecStoreGenericTuple(tuple, slot, true);
/*
* CDB: Label each row with a synthetic ctid if needed for subquery dedup.
*/
if (node->cdb_want_ctid &&
!TupIsNull(slot))
{
slot_set_ctid_from_fake(slot, &node->cdb_fake_ctid);
}
}
else
{
ExecClearTuple(slot);
if (!node->ss.ps.delayEagerFree)
{
ExecEagerFreeExternalScan(node);
}
}
return slot;
}
/* ----------------------------------------------------------------
* SubqueryNext
*
* This is a workhorse for ExecSubqueryScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
SubqueryNext(SubqueryScanState *node)
{
TupleTableSlot *slot;
/*
* We need not support EvalPlanQual here, since we are not scanning a real
* relation.
*/
/*
* Get the next tuple from the sub-query.
*/
slot = ExecProcNode(node->subplan);
/*
* We just overwrite our ScanTupleSlot with the subplan's result slot,
* rather than expending the cycles for ExecCopySlot().
*/
node->ss.ss_ScanTupleSlot = slot;
/*
* CDB: Label each row with a synthetic ctid if needed for subquery dedup.
*/
if (node->cdb_want_ctid &&
!TupIsNull(slot))
{
slot_set_ctid_from_fake(slot, &node->cdb_fake_ctid);
}
if (!TupIsNull(slot))
{
Gpmon_M_Incr_Rows_Out(GpmonPktFromSubqueryScanState(node));
CheckSendPlanStateGpmonPkt(&node->ss.ps);
}
return slot;
}
