Example #1
0
/*
 * get_all_brokers
 *
 * Return a list of all brokers in pipeline_kafka_brokers
 */
static List *
get_all_brokers(void)
{
	HeapTuple tup = NULL;
	HeapScanDesc scan;
	Relation brokers = open_pipeline_kafka_brokers();
	TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(brokers));
	List *result = NIL;

	scan = heap_beginscan(brokers, GetTransactionSnapshot(), 0, NULL);
	while ((tup = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		char *host;
		Datum d;
		bool isnull;

		ExecStoreTuple(tup, slot, InvalidBuffer, false);
		d = slot_getattr(slot, BROKER_ATTR_HOST, &isnull);
		host = TextDatumGetCString(d);

		result = lappend(result, host);
	}

	ExecDropSingleTupleTableSlot(slot);
	heap_endscan(scan);
	heap_close(brokers, NoLock);

	return result;
}
Example #2
0
void
SpoolerInsert(Spooler *self, HeapTuple tuple)
{
	/* Spool keys in the tuple */
	ExecStoreTuple(tuple, self->slot, InvalidBuffer, false);
	IndexSpoolInsert(self->spools, self->slot, &(tuple->t_self), self->estate, true);
	BULKLOAD_PROFILE(&prof_writer_index);
}
/* ----------------------------------------------------------------
 *		FunctionNext
 *
 *		This is a workhorse for ExecFunctionScan
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
FunctionNext(FunctionScanState *node)
{
	TupleTableSlot *slot;
	EState	   *estate;
	ScanDirection direction;
	Tuplestorestate *tuplestorestate;
	bool		should_free;
	HeapTuple	heapTuple;

	/*
	 * get information from the estate and scan state
	 */
	estate = node->ss.ps.state;
	direction = estate->es_direction;

	tuplestorestate = node->tuplestorestate;

	/*
	 * If first time through, read all tuples from function and put them
	 * in a tuplestore. Subsequent calls just fetch tuples from
	 * tuplestore.
	 */
	if (tuplestorestate == NULL)
	{
		ExprContext *econtext = node->ss.ps.ps_ExprContext;
		TupleDesc	funcTupdesc;

		node->tuplestorestate = tuplestorestate =
			ExecMakeTableFunctionResult(node->funcexpr,
										econtext,
										node->tupdesc,
										&funcTupdesc);

		/*
		 * If function provided a tupdesc, cross-check it.	We only really
		 * need to do this for functions returning RECORD, but might as
		 * well do it always.
		 */
		if (funcTupdesc && !tupledesc_match(node->tupdesc, funcTupdesc))
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("query-specified return row and actual function return row do not match")));
	}

	/*
	 * Get the next tuple from tuplestore. Return NULL if no more tuples.
	 */
	heapTuple = tuplestore_getheaptuple(tuplestorestate,
										ScanDirectionIsForward(direction),
										&should_free);
	slot = node->ss.ss_ScanTupleSlot;
	return ExecStoreTuple(heapTuple, slot, InvalidBuffer, should_free);
}
Example #4
0
/* ----------------------------------------------------------------
 *		FunctionNext
 *
 *		This is a workhorse for ExecFunctionScan
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
FunctionNext(FunctionScanState *node)
{
	TupleTableSlot *slot;
	EState	   *estate;
	ScanDirection direction;
	Tuplestorestate *tuplestorestate;
	bool		should_free;
	HeapTuple	heapTuple;

	/*
	 * get information from the estate and scan state
	 */
	estate = node->ss.ps.state;
	direction = estate->es_direction;

	tuplestorestate = node->tuplestorestate;

	/*
	 * If first time through, read all tuples from function and put them in a
	 * tuplestore. Subsequent calls just fetch tuples from tuplestore.
	 */
	if (tuplestorestate == NULL)
	{
		ExprContext *econtext = node->ss.ps.ps_ExprContext;
		TupleDesc	funcTupdesc;

		node->tuplestorestate = tuplestorestate =
			ExecMakeTableFunctionResult(node->funcexpr,
										econtext,
										node->tupdesc,
										&funcTupdesc);

		/*
		 * If function provided a tupdesc, cross-check it.	We only really
		 * need to do this for functions returning RECORD, but might as well
		 * do it always.
		 */
		if (funcTupdesc)
			tupledesc_match(node->tupdesc, funcTupdesc);
	}

	/*
	 * Get the next tuple from tuplestore. Return NULL if no more tuples.
	 */
	heapTuple = tuplestore_getheaptuple(tuplestorestate,
										ScanDirectionIsForward(direction),
										&should_free);
	slot = node->ss.ss_ScanTupleSlot;
	if (heapTuple)
		return ExecStoreTuple(heapTuple, slot, InvalidBuffer, should_free);
	else
		return ExecClearTuple(slot);
}
Example #5
0
/* ----------------------------------------------------------------
 *		SeqNext
 *
 *		This is a workhorse for ExecSeqScan
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
SeqNext(SeqScanState *node)
{
	HeapTuple	tuple;
	HeapScanDesc scandesc;
	EState	   *estate;
	ScanDirection direction;
	TupleTableSlot *slot;

	/*
	 * get information from the estate and scan state
	 */
	scandesc = node->ss.ss_currentScanDesc;
	estate = node->ss.ps.state;
	direction = estate->es_direction;
	slot = node->ss.ss_ScanTupleSlot;

	if (scandesc == NULL)
	{
		/*
		 * We reach here if the scan is not parallel, or if we're executing a
		 * scan that was intended to be parallel serially.
		 */
		scandesc = heap_beginscan(node->ss.ss_currentRelation,
								  estate->es_snapshot,
								  0, NULL);
		node->ss.ss_currentScanDesc = scandesc;
	}

	/*
	 * get the next tuple from the table
	 */
	tuple = heap_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)
		ExecStoreTuple(tuple,	/* tuple to store */
					   slot,	/* slot to store in */
					   scandesc->rs_cbuf,	/* buffer associated with this
											 * tuple */
					   false);	/* don't pfree this pointer */
	else
		ExecClearTuple(slot);

	return slot;
}
Example #6
0
/*
 * load_consumer_offsets
 *
 * Load all offsets for all of this consumer's partitions
 */
static void
load_consumer_offsets(KafkaConsumer *consumer, struct rd_kafka_metadata_topic *meta, int64_t offset)
{
	MemoryContext old;
	ScanKeyData skey[1];
	HeapTuple tup = NULL;
	HeapScanDesc scan;
	Relation offsets = open_pipeline_kafka_offsets();
	TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(offsets));
	int i;

	ScanKeyInit(&skey[0], OFFSETS_ATTR_CONSUMER, BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(consumer->id));
	scan = heap_beginscan(offsets, GetTransactionSnapshot(), 1, skey);

	old = MemoryContextSwitchTo(CacheMemoryContext);
	consumer->offsets = palloc0(meta->partition_cnt * sizeof(int64_t));
	MemoryContextSwitchTo(old);

	/* by default, begin consuming from the end of a stream */
	for (i = 0; i < meta->partition_cnt; i++)
		consumer->offsets[i] = offset;

	consumer->num_partitions = meta->partition_cnt;

	while ((tup = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		Datum d;
		bool isnull;
		int partition;
		ExecStoreTuple(tup, slot, InvalidBuffer, false);

		d = slot_getattr(slot, OFFSETS_ATTR_PARTITION, &isnull);
		partition = DatumGetInt32(d);

		if(partition > consumer->num_partitions)
			elog(ERROR, "invalid partition id: %d", partition);

		if (offset == RD_KAFKA_OFFSET_NULL)
		{
			d = slot_getattr(slot, OFFSETS_ATTR_OFFSET, &isnull);
			if (isnull)
				offset = RD_KAFKA_OFFSET_END;
			else
				offset = DatumGetInt64(d);
		}

		consumer->offsets[partition] = DatumGetInt64(offset);
	}

	ExecDropSingleTupleTableSlot(slot);
	heap_endscan(scan);
	heap_close(offsets, RowExclusiveLock);
}
Example #7
0
/*
 * ExecRecFetch -- fetch next potential tuple
 *
 * This routine is concerned with substituting a test tuple if we are
 * inside an EvalPlanQual recheck.	If we aren't, just execute
 * the access method's next-tuple routine.
 *
 * This method is identical to ExecScanFetch, we just want to avoid
 * possible duplicate function issues.
 */
static inline TupleTableSlot *
ExecRecFetch(ScanState *node,
			  ExecScanAccessMtd accessMtd,
			  ExecScanRecheckMtd recheckMtd)
{
	EState	   *estate = node->ps.state;

	if (estate->es_epqTuple != NULL)
	{
		/*
		 * We are inside an EvalPlanQual recheck.  Return the test tuple if
		 * one is available, after rechecking any access-method-specific
		 * conditions.
		 */
		Index		scanrelid = ((Scan *) node->ps.plan)->scanrelid;

		Assert(scanrelid > 0);
		if (estate->es_epqTupleSet[scanrelid - 1])
		{
			TupleTableSlot *slot = node->ss_ScanTupleSlot;

			/* Return empty slot if we already returned a tuple */
			if (estate->es_epqScanDone[scanrelid - 1])
				return ExecClearTuple(slot);
			/* Else mark to remember that we shouldn't return more */
			estate->es_epqScanDone[scanrelid - 1] = true;

			/* Return empty slot if we haven't got a test tuple */
			if (estate->es_epqTuple[scanrelid - 1] == NULL)
				return ExecClearTuple(slot);

			/* Store test tuple in the plan node's scan slot */
			ExecStoreTuple(estate->es_epqTuple[scanrelid - 1],
						   slot, InvalidBuffer, false);

			/* Check if it meets the access-method conditions */
			if (!(*recheckMtd) (node, slot))
				ExecClearTuple(slot);	/* would not be returned by scan */

			return slot;
		}
	}

	/*
	 * Run the node-type-specific access method function to get the next tuple
	 */
	return (*accessMtd) (node);
}
Example #8
0
/*
 * Read the next tuple.  We might fetch a tuple from one of the tuple queues
 * using gather_readnext, or if no tuple queue contains a tuple and the
 * single_copy flag is not set, we might generate one locally instead.
 */
static TupleTableSlot *
gather_getnext(GatherState *gatherstate)
{
	PlanState  *outerPlan = outerPlanState(gatherstate);
	TupleTableSlot *outerTupleSlot;
	TupleTableSlot *fslot = gatherstate->funnel_slot;
	HeapTuple	tup;

	while (gatherstate->nreaders > 0 || gatherstate->need_to_scan_locally)
	{
		CHECK_FOR_INTERRUPTS();

		if (gatherstate->nreaders > 0)
		{
			tup = gather_readnext(gatherstate);

			if (HeapTupleIsValid(tup))
			{
				ExecStoreTuple(tup, /* tuple to store */
							   fslot,	/* slot in which to store the tuple */
							   InvalidBuffer,	/* buffer associated with this
												 * tuple */
							   true);	/* pfree tuple when done with it */
				return fslot;
			}
		}

		if (gatherstate->need_to_scan_locally)
		{
			EState *estate = gatherstate->ps.state;

			/* Install our DSA area while executing the plan. */
			estate->es_query_dsa =
				gatherstate->pei ? gatherstate->pei->area : NULL;
			outerTupleSlot = ExecProcNode(outerPlan);
			estate->es_query_dsa = NULL;

			if (!TupIsNull(outerTupleSlot))
				return outerTupleSlot;

			gatherstate->need_to_scan_locally = false;
		}
	}

	return ExecClearTuple(fslot);
}
Example #9
0
/* --------------------------------
 *		ExecCopySlot
 *			Copy the source slot's contents into the destination slot.
 *
 *		The destination acquires a private copy that will not go away
 *		if the source is cleared.
 *
 *		The caller must ensure the slots have compatible tupdescs.
 * --------------------------------
 */
TupleTableSlot *
ExecCopySlot(TupleTableSlot *dstslot, TupleTableSlot *srcslot)
{
	HeapTuple	newTuple;
	MemoryContext oldContext;

	/*
	 * There might be ways to optimize this when the source is virtual, but
	 * for now just always build a physical copy.  Make sure it is in the
	 * right context.
	 */
	oldContext = MemoryContextSwitchTo(dstslot->tts_mcxt);
	newTuple = ExecCopySlotTuple(srcslot);
	MemoryContextSwitchTo(oldContext);

	return ExecStoreTuple(newTuple, dstslot, InvalidBuffer, true);
}
Example #10
0
/*
 * CopyIntoStream
 *
 * COPY events to a stream from an input source
 */
void
CopyIntoStream(Relation rel, TupleDesc desc, HeapTuple *tuples, int ntuples)
{
	bool snap = ActiveSnapshotSet();
	ResultRelInfo rinfo;
	StreamInsertState *sis;

	MemSet(&rinfo, 0, sizeof(ResultRelInfo));
	rinfo.ri_RangeTableIndex = 1; /* dummy */
	rinfo.ri_TrigDesc = NULL;
	rinfo.ri_RelationDesc = rel;

	if (snap)
		PopActiveSnapshot();

	BeginStreamModify(NULL, &rinfo, list_make1(desc), 0, 0);
	sis = (StreamInsertState *) rinfo.ri_FdwState;
	Assert(sis);

	if (sis->queries)
	{
		TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(rel));
		int i;

		for (i = 0; i < ntuples; i++)
		{
			ExecStoreTuple(tuples[i], slot, InvalidBuffer, false);
			ExecStreamInsert(NULL, &rinfo, slot, NULL);
			ExecClearTuple(slot);
		}

		ExecDropSingleTupleTableSlot(slot);

		Assert(sis->ntups == ntuples);
		pgstat_increment_cq_write(ntuples, sis->nbytes);
	}

	EndStreamModify(NULL, &rinfo);

	if (snap)
		PushActiveSnapshot(GetTransactionSnapshot());
}
Example #11
0
/*
 * Read the next tuple.  We might fetch a tuple from one of the tuple queues
 * using gather_readnext, or if no tuple queue contains a tuple and the
 * single_copy flag is not set, we might generate one locally instead.
 */
static TupleTableSlot *
gather_getnext(GatherState *gatherstate)
{
	PlanState  *outerPlan = outerPlanState(gatherstate);
	TupleTableSlot *outerTupleSlot;
	TupleTableSlot *fslot = gatherstate->funnel_slot;
	HeapTuple	tup;

	while (gatherstate->reader != NULL || gatherstate->need_to_scan_locally)
	{
		if (gatherstate->reader != NULL)
		{
			tup = gather_readnext(gatherstate);

			if (HeapTupleIsValid(tup))
			{
				ExecStoreTuple(tup,		/* tuple to store */
							   fslot,	/* slot in which to store the tuple */
							   InvalidBuffer,	/* buffer associated with this
												 * tuple */
							   true);	/* pfree this pointer if not from heap */

				return fslot;
			}
		}

		if (gatherstate->need_to_scan_locally)
		{
			outerTupleSlot = ExecProcNode(outerPlan);

			if (!TupIsNull(outerTupleSlot))
				return outerTupleSlot;

			gatherstate->need_to_scan_locally = false;
		}
	}

	return ExecClearTuple(fslot);
}
Example #12
0
HeapTuple
CheckerConstraints(Checker *checker, HeapTuple tuple, int *parsing_field)
{
	if (checker->has_constraints)
	{
		*parsing_field = 0;

		/* Place tuple in tuple slot */
		ExecStoreTuple(tuple, checker->slot, InvalidBuffer, false);

		/* Check the constraints of the tuple */
		ExecConstraints(checker->resultRelInfo, checker->slot, checker->estate);
	}
	else if (checker->has_not_null && HeapTupleHasNulls(tuple))
	{
		/*
		 * Even if CHECK_CONSTRAINTS is not specified, check NOT NULL constraint
		 */
		TupleDesc	desc = checker->desc;
		int			i;

		for (i = 0; i < desc->natts; i++)
		{
			if (desc->attrs[i]->attnotnull &&
				att_isnull(i, tuple->t_data->t_bits))
			{
				*parsing_field = i + 1;	/* 1 origin */
				ereport(ERROR,
						(errcode(ERRCODE_NOT_NULL_VIOLATION),
						 errmsg("null value in column \"%s\" violates not-null constraint",
						NameStr(desc->attrs[i]->attname))));
			}
		}
	}

	return tuple;
}
Example #13
0
/* --------------------------------
 *		ExecMaterializeSlot
 *			Force a slot into the "materialized" state.
 *
 *		This causes the slot's tuple to be a local copy not dependent on
 *		any external storage.  A pointer to the contained tuple is returned.
 *
 *		A typical use for this operation is to prepare a computed tuple
 *		for being stored on disk.  The original data may or may not be
 *		virtual, but in any case we need a private copy for heap_insert
 *		to scribble on.
 * --------------------------------
 */
HeapTuple
ExecMaterializeSlot(TupleTableSlot *slot)
{
	HeapTuple	newTuple;
	MemoryContext oldContext;

	/*
	 * sanity checks
	 */
	Assert(slot != NULL);
	Assert(!slot->tts_isempty);

	/*
	 * If we have a physical tuple, and it's locally palloc'd, we have nothing
	 * to do.
	 */
	if (slot->tts_tuple && slot->tts_shouldFree)
		return slot->tts_tuple;

	/*
	 * Otherwise, copy or build a tuple, and then store it as the new slot
	 * value.  (Note: tts_nvalid will be reset to zero here.  There are cases
	 * in which this could be optimized but it's probably not worth worrying
	 * about.)
	 *
	 * We may be called in a context that is shorter-lived than the tuple
	 * slot, but we have to ensure that the materialized tuple will survive
	 * anyway.
	 */
	oldContext = MemoryContextSwitchTo(slot->tts_mcxt);
	newTuple = ExecCopySlotTuple(slot);
	MemoryContextSwitchTo(oldContext);

	ExecStoreTuple(newTuple, slot, InvalidBuffer, true);

	return slot->tts_tuple;
}
Example #14
0
/*
 * save_consumer_state
 *
 * Saves the given consumer's state to pipeline_kafka_consumers
 */
static void
save_consumer_state(KafkaConsumer *consumer, int partition_group)
{
	ScanKeyData skey[1];
	HeapTuple tup = NULL;
	HeapScanDesc scan;
	Relation offsets = open_pipeline_kafka_offsets();
	Datum values[OFFSETS_RELATION_NATTS];
	bool nulls[OFFSETS_RELATION_NATTS];
	bool replace[OFFSETS_RELATION_NATTS];
	bool updated[consumer->num_partitions];
	TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(offsets));
	int partition;

	MemSet(updated, false, sizeof(updated));

	ScanKeyInit(&skey[0], OFFSETS_ATTR_CONSUMER, BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(consumer->id));
	scan = heap_beginscan(offsets, GetTransactionSnapshot(), 1, skey);

	/* update any existing offset rows */
	while ((tup = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		Datum d;
		bool isnull;
		int partition;
		HeapTuple modified;

		ExecStoreTuple(tup, slot, InvalidBuffer, false);
		d = slot_getattr(slot, OFFSETS_ATTR_PARTITION, &isnull);
		partition = DatumGetInt32(d);

		/* we only want to update the offsets we're responsible for */
		if (partition % consumer->parallelism != partition_group)
			continue;

		MemSet(nulls, false, sizeof(nulls));
		MemSet(replace, false, sizeof(nulls));

		values[OFFSETS_ATTR_OFFSET - 1] = Int64GetDatum(consumer->offsets[partition]);
		replace[OFFSETS_ATTR_OFFSET - 1] = true;
		updated[partition] = true;

		modified = heap_modify_tuple(tup, RelationGetDescr(offsets), values, nulls, replace);
		simple_heap_update(offsets, &modified->t_self, modified);
	}

	heap_endscan(scan);

	/* now insert any offset rows that didn't already exist */
	for (partition = 0; partition < consumer->num_partitions; partition++)
	{
		if (updated[partition])
			continue;

		if (partition % consumer->parallelism != partition_group)
			continue;

		values[OFFSETS_ATTR_CONSUMER - 1] = ObjectIdGetDatum(consumer->id);
		values[OFFSETS_ATTR_PARTITION - 1] = Int32GetDatum(partition);
		values[OFFSETS_ATTR_OFFSET - 1] = Int64GetDatum(consumer->offsets[partition]);

		MemSet(nulls, false, sizeof(nulls));

		tup = heap_form_tuple(RelationGetDescr(offsets), values, nulls);
		simple_heap_insert(offsets, tup);
	}

	ExecDropSingleTupleTableSlot(slot);
	heap_close(offsets, NoLock);
}
Example #15
0
/* ----------------------------------------------------------------
 *		SeqNext
 *
 *		This is a workhorse for ExecSeqScan
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
SeqNext(SeqScanState *node)
{
	HeapTuple	tuple;
	HeapScanDesc scandesc;
	Index		scanrelid;
	EState	   *estate;
	ScanDirection direction;
	TupleTableSlot *slot;

	/*
	 * get information from the estate and scan state
	 */
	estate = node->ps.state;
	scandesc = node->ss_currentScanDesc;
	scanrelid = ((SeqScan *) node->ps.plan)->scanrelid;
	direction = estate->es_direction;
	slot = node->ss_ScanTupleSlot;

	/*
	 * Check if we are evaluating PlanQual for tuple of this relation.
	 * Additional checking is not good, but no other way for now. We could
	 * introduce new nodes for this case and handle SeqScan --> NewNode
	 * switching in Init/ReScan plan...
	 */
	if (estate->es_evTuple != NULL &&
		estate->es_evTuple[scanrelid - 1] != NULL)
	{
		if (estate->es_evTupleNull[scanrelid - 1])
			return ExecClearTuple(slot);

		ExecStoreTuple(estate->es_evTuple[scanrelid - 1],
					   slot, InvalidBuffer, false);

		/*
		 * Note that unlike IndexScan, SeqScan never use keys in
		 * heap_beginscan (and this is very bad) - so, here we do not check
		 * are keys ok or not.
		 */

		/* Flag for the next call that no more tuples */
		estate->es_evTupleNull[scanrelid - 1] = true;
		return slot;
	}

	/*
	 * get the next tuple from the access methods
	 */
	scandesc->estate=estate;
	scandesc->slot=slot;
	scandesc->qual=node->ps.qual;
	tuple = heap_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)
		ExecStoreTuple(tuple,	/* tuple to store */
					   slot,	/* slot to store in */
					   scandesc->rs_cbuf,		/* buffer associated with this
												 * tuple */
					   false);	/* don't pfree this pointer */
	else
		ExecClearTuple(slot);

	return slot;
}
Example #16
0
/* ----------------------------------------------------------------
 *		ExecSort
 *
 *		Sorts tuples from the outer subtree of the node using tuplesort,
 *		which saves the results in a temporary file or memory. After the
 *		initial call, returns a tuple from the file with each call.
 *
 *		Conditions:
 *		  -- none.
 *
 *		Initial States:
 *		  -- the outer child is prepared to return the first tuple.
 * ----------------------------------------------------------------
 */
TupleTableSlot *
ExecSort(SortState *node)
{
	EState	   *estate;
	ScanDirection dir;
	Tuplesortstate *tuplesortstate;
	HeapTuple	heapTuple;
	TupleTableSlot *slot;
	bool		should_free;

	/*
	 * get state info from node
	 */
	SO1_printf("ExecSort: %s\n",
			   "entering routine");

	estate = node->ss.ps.state;
	dir = estate->es_direction;
	tuplesortstate = (Tuplesortstate *) node->tuplesortstate;

	/*
	 * If first time through, read all tuples from outer plan and pass them to
	 * tuplesort.c. Subsequent calls just fetch tuples from tuplesort.
	 */

	if (!node->sort_Done)
	{
		Sort	   *plannode = (Sort *) node->ss.ps.plan;
		PlanState  *outerNode;
		TupleDesc	tupDesc;

		SO1_printf("ExecSort: %s\n",
				   "sorting subplan");

		/*
		 * Want to scan subplan in the forward direction while creating the
		 * sorted data.
		 */
		estate->es_direction = ForwardScanDirection;

		/*
		 * Initialize tuplesort module.
		 */
		SO1_printf("ExecSort: %s\n",
				   "calling tuplesort_begin");

		outerNode = outerPlanState(node);
		tupDesc = ExecGetResultType(outerNode);

		tuplesortstate = tuplesort_begin_heap(tupDesc,
											  plannode->numCols,
											  plannode->sortOperators,
											  plannode->sortColIdx,
											  work_mem,
											  node->randomAccess);
		node->tuplesortstate = (void *) tuplesortstate;

		/*
		 * Scan the subplan and feed all the tuples to tuplesort.
		 */

		for (;;)
		{
			slot = ExecProcNode(outerNode);

			if (TupIsNull(slot))
				break;

			tuplesort_puttuple(tuplesortstate,
							   (void *) ExecFetchSlotTuple(slot));
		}

		/*
		 * Complete the sort.
		 */
		tuplesort_performsort(tuplesortstate);

		/*
		 * restore to user specified direction
		 */
		estate->es_direction = dir;

		/*
		 * finally set the sorted flag to true
		 */
		node->sort_Done = true;
		SO1_printf("ExecSort: %s\n", "sorting done");
	}

	SO1_printf("ExecSort: %s\n",
			   "retrieving tuple from tuplesort");

	/*
	 * Get the first or next tuple from tuplesort. Returns NULL if no more
	 * tuples.
	 */
	heapTuple = tuplesort_getheaptuple(tuplesortstate,
									   ScanDirectionIsForward(dir),
									   &should_free);

	slot = node->ss.ps.ps_ResultTupleSlot;
	if (heapTuple)
		return ExecStoreTuple(heapTuple, slot, InvalidBuffer, should_free);
	else
		return ExecClearTuple(slot);
}
Example #17
0
Datum
pipeline_stream_insert(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	Trigger *trig = trigdata->tg_trigger;
	HeapTuple tup;
	List *fdw_private;
	int i;
	ResultRelInfo rinfo;

	if (trig->tgnargs < 1)
		elog(ERROR, "pipeline_stream_insert: must be provided a stream name");

	/* make sure it's called as a trigger */
	if (!CALLED_AS_TRIGGER(fcinfo))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("pipeline_stream_insert: must be called as trigger")));

	/* and that it's called on update or insert */
	if (!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event) && !TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("pipeline_stream_insert: must be called on insert or update")));

	/* and that it's called for each row */
	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("pipeline_stream_insert: must be called for each row")));

	/* and that it's called after insert or update */
	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("pipeline_stream_insert: must be called after insert or update")));

	if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
		tup = trigdata->tg_newtuple;
	else
		tup = trigdata->tg_trigtuple;

	fdw_private = list_make1(RelationGetDescr(trigdata->tg_relation));

	MemSet(&rinfo, 0, sizeof(ResultRelInfo));
	rinfo.ri_RangeTableIndex = 1; /* dummy */
	rinfo.ri_TrigDesc = NULL;

	for (i = 0; i < trig->tgnargs; i++)
	{
		RangeVar *stream;
		Relation rel;
		StreamInsertState *sis;

		stream = makeRangeVarFromNameList(textToQualifiedNameList(cstring_to_text(trig->tgargs[i])));
		rel = heap_openrv(stream, AccessShareLock);

		rinfo.ri_RelationDesc = rel;

		BeginStreamModify(NULL, &rinfo, fdw_private, 0, 0);
		sis = (StreamInsertState *) rinfo.ri_FdwState;
		Assert(sis);

		if (sis->queries)
		{
			TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(rel));

			ExecStoreTuple(tup, slot, InvalidBuffer, false);
			ExecStreamInsert(NULL, &rinfo, slot, NULL);
			ExecClearTuple(slot);

			ExecDropSingleTupleTableSlot(slot);
			pgstat_report_streamstat(true);
		}

		EndStreamModify(NULL, &rinfo);
		heap_close(rel, AccessShareLock);
	}

	return PointerGetDatum(tup);
}
Example #18
0
/*
 * Search the relation 'rel' for tuple using the index.
 *
 * If a matching tuple is found, lock it with lockmode, fill the slot with its
 * contents, and return true.  Return false otherwise.
 */
bool
RelationFindReplTupleByIndex(Relation rel, Oid idxoid,
							 LockTupleMode lockmode,
							 TupleTableSlot *searchslot,
							 TupleTableSlot *outslot)
{
	HeapTuple	scantuple;
	ScanKeyData skey[INDEX_MAX_KEYS];
	IndexScanDesc scan;
	SnapshotData snap;
	TransactionId xwait;
	Relation	idxrel;
	bool		found;

	/* Open the index. */
	idxrel = index_open(idxoid, RowExclusiveLock);

	/* Start an index scan. */
	InitDirtySnapshot(snap);
	scan = index_beginscan(rel, idxrel, &snap,
						   RelationGetNumberOfAttributes(idxrel),
						   0);

	/* Build scan key. */
	build_replindex_scan_key(skey, rel, idxrel, searchslot);

retry:
	found = false;

	index_rescan(scan, skey, RelationGetNumberOfAttributes(idxrel), NULL, 0);

	/* Try to find the tuple */
	if ((scantuple = index_getnext(scan, ForwardScanDirection)) != NULL)
	{
		found = true;
		ExecStoreTuple(scantuple, outslot, InvalidBuffer, false);
		ExecMaterializeSlot(outslot);

		xwait = TransactionIdIsValid(snap.xmin) ?
			snap.xmin : snap.xmax;

		/*
		 * If the tuple is locked, wait for locking transaction to finish and
		 * retry.
		 */
		if (TransactionIdIsValid(xwait))
		{
			XactLockTableWait(xwait, NULL, NULL, XLTW_None);
			goto retry;
		}
	}

	/* Found tuple, try to lock it in the lockmode. */
	if (found)
	{
		Buffer		buf;
		HeapUpdateFailureData hufd;
		HTSU_Result res;
		HeapTupleData locktup;

		ItemPointerCopy(&outslot->tts_tuple->t_self, &locktup.t_self);

		PushActiveSnapshot(GetLatestSnapshot());

		res = heap_lock_tuple(rel, &locktup, GetCurrentCommandId(false),
							  lockmode,
							  LockWaitBlock,
							  false /* don't follow updates */ ,
							  &buf, &hufd);
		/* the tuple slot already has the buffer pinned */
		ReleaseBuffer(buf);

		PopActiveSnapshot();

		switch (res)
		{
			case HeapTupleMayBeUpdated:
				break;
			case HeapTupleUpdated:
				/* XXX: Improve handling here */
				ereport(LOG,
						(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
						 errmsg("concurrent update, retrying")));
				goto retry;
			case HeapTupleInvisible:
				elog(ERROR, "attempted to lock invisible tuple");
			default:
				elog(ERROR, "unexpected heap_lock_tuple status: %u", res);
				break;
		}
	}

	index_endscan(scan);

	/* Don't release lock until commit. */
	index_close(idxrel, NoLock);

	return found;
}
Example #19
0
/*
 * Handle UPDATE message.
 *
 * TODO: FDW support
 */
static void
apply_handle_update(StringInfo s)
{
	LogicalRepRelMapEntry *rel;
	LogicalRepRelId relid;
	Oid			idxoid;
	EState	   *estate;
	EPQState	epqstate;
	LogicalRepTupleData oldtup;
	LogicalRepTupleData newtup;
	bool		has_oldtup;
	TupleTableSlot *localslot;
	TupleTableSlot *remoteslot;
	bool		found;
	MemoryContext oldctx;

	ensure_transaction();

	relid = logicalrep_read_update(s, &has_oldtup, &oldtup,
								   &newtup);
	rel = logicalrep_rel_open(relid, RowExclusiveLock);
	if (!should_apply_changes_for_rel(rel))
	{
		/*
		 * The relation can't become interesting in the middle of the
		 * transaction so it's safe to unlock it.
		 */
		logicalrep_rel_close(rel, RowExclusiveLock);
		return;
	}

	/* Check if we can do the update. */
	check_relation_updatable(rel);

	/* Initialize the executor state. */
	estate = create_estate_for_relation(rel);
	remoteslot = ExecInitExtraTupleSlot(estate,
										RelationGetDescr(rel->localrel));
	localslot = ExecInitExtraTupleSlot(estate,
									   RelationGetDescr(rel->localrel));
	EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);

	PushActiveSnapshot(GetTransactionSnapshot());
	ExecOpenIndices(estate->es_result_relation_info, false);

	/* Build the search tuple. */
	oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
	slot_store_cstrings(remoteslot, rel,
						has_oldtup ? oldtup.values : newtup.values);
	MemoryContextSwitchTo(oldctx);

	/*
	 * Try to find tuple using either replica identity index, primary key or
	 * if needed, sequential scan.
	 */
	idxoid = GetRelationIdentityOrPK(rel->localrel);
	Assert(OidIsValid(idxoid) ||
		   (rel->remoterel.replident == REPLICA_IDENTITY_FULL && has_oldtup));

	if (OidIsValid(idxoid))
		found = RelationFindReplTupleByIndex(rel->localrel, idxoid,
											 LockTupleExclusive,
											 remoteslot, localslot);
	else
		found = RelationFindReplTupleSeq(rel->localrel, LockTupleExclusive,
										 remoteslot, localslot);

	ExecClearTuple(remoteslot);

	/*
	 * Tuple found.
	 *
	 * Note this will fail if there are other conflicting unique indexes.
	 */
	if (found)
	{
		/* Process and store remote tuple in the slot */
		oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
		ExecStoreTuple(localslot->tts_tuple, remoteslot, InvalidBuffer, false);
		slot_modify_cstrings(remoteslot, rel, newtup.values, newtup.changed);
		MemoryContextSwitchTo(oldctx);

		EvalPlanQualSetSlot(&epqstate, remoteslot);

		/* Do the actual update. */
		ExecSimpleRelationUpdate(estate, &epqstate, localslot, remoteslot);
	}
	else
	{
		/*
		 * The tuple to be updated could not be found.
		 *
		 * TODO what to do here, change the log level to LOG perhaps?
		 */
		elog(DEBUG1,
			 "logical replication did not find row for update "
			 "in replication target relation \"%s\"",
			 RelationGetRelationName(rel->localrel));
	}

	/* Cleanup. */
	ExecCloseIndices(estate->es_result_relation_info);
	PopActiveSnapshot();

	/* Handle queued AFTER triggers. */
	AfterTriggerEndQuery(estate);

	EvalPlanQualEnd(&epqstate);
	ExecResetTupleTable(estate->es_tupleTable, false);
	FreeExecutorState(estate);

	logicalrep_rel_close(rel, NoLock);

	CommandCounterIncrement();
}
Example #20
0
/*
 * Search the relation 'rel' for tuple using the sequential scan.
 *
 * If a matching tuple is found, lock it with lockmode, fill the slot with its
 * contents, and return true.  Return false otherwise.
 *
 * Note that this stops on the first matching tuple.
 *
 * This can obviously be quite slow on tables that have more than few rows.
 */
bool
RelationFindReplTupleSeq(Relation rel, LockTupleMode lockmode,
						 TupleTableSlot *searchslot, TupleTableSlot *outslot)
{
	HeapTuple	scantuple;
	HeapScanDesc scan;
	SnapshotData snap;
	TransactionId xwait;
	bool		found;
	TupleDesc	desc = RelationGetDescr(rel);

	Assert(equalTupleDescs(desc, outslot->tts_tupleDescriptor));

	/* Start an index scan. */
	InitDirtySnapshot(snap);
	scan = heap_beginscan(rel, &snap, 0, NULL);

retry:
	found = false;

	heap_rescan(scan, NULL);

	/* Try to find the tuple */
	while ((scantuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		if (!tuple_equals_slot(desc, scantuple, searchslot))
			continue;

		found = true;
		ExecStoreTuple(scantuple, outslot, InvalidBuffer, false);
		ExecMaterializeSlot(outslot);

		xwait = TransactionIdIsValid(snap.xmin) ?
			snap.xmin : snap.xmax;

		/*
		 * If the tuple is locked, wait for locking transaction to finish and
		 * retry.
		 */
		if (TransactionIdIsValid(xwait))
		{
			XactLockTableWait(xwait, NULL, NULL, XLTW_None);
			goto retry;
		}
	}

	/* Found tuple, try to lock it in the lockmode. */
	if (found)
	{
		Buffer		buf;
		HeapUpdateFailureData hufd;
		HTSU_Result res;
		HeapTupleData locktup;

		ItemPointerCopy(&outslot->tts_tuple->t_self, &locktup.t_self);

		PushActiveSnapshot(GetLatestSnapshot());

		res = heap_lock_tuple(rel, &locktup, GetCurrentCommandId(false),
							  lockmode,
							  LockWaitBlock,
							  false /* don't follow updates */ ,
							  &buf, &hufd);
		/* the tuple slot already has the buffer pinned */
		ReleaseBuffer(buf);

		PopActiveSnapshot();

		switch (res)
		{
			case HeapTupleMayBeUpdated:
				break;
			case HeapTupleUpdated:
				/* XXX: Improve handling here */
				ereport(LOG,
						(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
						 errmsg("concurrent update, retrying")));
				goto retry;
			case HeapTupleInvisible:
				elog(ERROR, "attempted to lock invisible tuple");
			default:
				elog(ERROR, "unexpected heap_lock_tuple status: %u", res);
				break;
		}
	}

	heap_endscan(scan);

	return found;
}
Example #21
0
/* ----------------------------------------------------------------
 *	   ExecProcAppend
 *
 *		Handles the iteration over the multiple scans.
 *
 *	   NOTE: Can't call this ExecAppend, that name is used in execMain.
 * ----------------------------------------------------------------
 */
TupleTableSlot *
ExecProcAppend(AppendState *node)
{
	EState	   *estate;
	int			whichplan;
	PlanState  *subnode;
	TupleTableSlot *result;
	TupleTableSlot *result_slot;
	ScanDirection direction;

	/*
	 * get information from the node
	 */
	estate = node->ps.state;
	direction = estate->es_direction;
	whichplan = node->as_whichplan;
	result_slot = node->ps.ps_ResultTupleSlot;

	/*
	 * figure out which subplan we are currently processing
	 */
	subnode = node->appendplans[whichplan];

	/*
	 * get a tuple from the subplan
	 */
	result = ExecProcNode(subnode);

	if (!TupIsNull(result))
	{
		/*
		 * if the subplan gave us something then place a copy of whatever
		 * we get into our result slot and return it.
		 *
		 * Note we rely on the subplan to retain ownership of the tuple for
		 * as long as we need it --- we don't copy it.
		 */
		return ExecStoreTuple(result->val, result_slot, InvalidBuffer, false);
	}
	else
	{
		/*
		 * .. go on to the "next" subplan in the appropriate direction and
		 * try processing again (recursively)
		 */
		if (ScanDirectionIsForward(direction))
			node->as_whichplan++;
		else
			node->as_whichplan--;

		/*
		 * return something from next node or an empty slot if all of our
		 * subplans have been exhausted.
		 */
		if (exec_append_initialize_next(node))
		{
			ExecSetSlotDescriptorIsNew(result_slot, true);
			return ExecProcAppend(node);
		}
		else
			return ExecClearTuple(result_slot);
	}
}
/* ----------------------------------------------------------------
 *		BitmapHeapNext
 *
 *		Retrieve next tuple from the BitmapHeapScan node's currentRelation
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
BitmapHeapNext(BitmapHeapScanState *node)
{
	EState	   *estate;
	ExprContext *econtext;
	HeapScanDesc scan;
	Index		scanrelid;
	TIDBitmap  *tbm;
	TBMIterateResult *tbmres;
	OffsetNumber targoffset;
	TupleTableSlot *slot;

	/*
	 * extract necessary information from index scan node
	 */
	estate = node->ss.ps.state;
	econtext = node->ss.ps.ps_ExprContext;
	slot = node->ss.ss_ScanTupleSlot;
	scan = node->ss.ss_currentScanDesc;
	scanrelid = ((BitmapHeapScan *) node->ss.ps.plan)->scan.scanrelid;
	tbm = node->tbm;
	tbmres = node->tbmres;

	/*
	 * Check if we are evaluating PlanQual for tuple of this relation.
	 * Additional checking is not good, but no other way for now. We could
	 * introduce new nodes for this case and handle IndexScan --> NewNode
	 * switching in Init/ReScan plan...
	 */
	if (estate->es_evTuple != NULL &&
		estate->es_evTuple[scanrelid - 1] != NULL)
	{
		if (estate->es_evTupleNull[scanrelid - 1])
			return ExecClearTuple(slot);

		ExecStoreTuple(estate->es_evTuple[scanrelid - 1],
					   slot, InvalidBuffer, false);

		/* Does the tuple meet the original qual conditions? */
		econtext->ecxt_scantuple = slot;

		ResetExprContext(econtext);

		if (!ExecQual(node->bitmapqualorig, econtext, false))
			ExecClearTuple(slot);		/* would not be returned by scan */

		/* Flag for the next call that no more tuples */
		estate->es_evTupleNull[scanrelid - 1] = true;

		return slot;
	}

	/*
	 * If we haven't yet performed the underlying index scan, do it, and
	 * prepare the bitmap to be iterated over.
	 */
	if (tbm == NULL)
	{
		tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));

		if (!tbm || !IsA(tbm, TIDBitmap))
			elog(ERROR, "unrecognized result from subplan");

		node->tbm = tbm;
		node->tbmres = tbmres = NULL;

		tbm_begin_iterate(tbm);
	}

	for (;;)
	{
		Page		dp;
		ItemId		lp;

		/*
		 * Get next page of results if needed
		 */
		if (tbmres == NULL)
		{
			node->tbmres = tbmres = tbm_iterate(tbm);
			if (tbmres == NULL)
			{
				/* no more entries in the bitmap */
				break;
			}

			/*
			 * Ignore any claimed entries past what we think is the end of the
			 * relation.  (This is probably not necessary given that we got at
			 * least AccessShareLock on the table before performing any of the
			 * indexscans, but let's be safe.)
			 */
			if (tbmres->blockno >= scan->rs_nblocks)
			{
				node->tbmres = tbmres = NULL;
				continue;
			}

			/*
			 * Fetch the current heap page and identify candidate tuples.
			 */
			bitgetpage(scan, tbmres);

			/*
			 * Set rs_cindex to first slot to examine
			 */
			scan->rs_cindex = 0;
		}
		else
		{
			/*
			 * Continuing in previously obtained page; advance rs_cindex
			 */
			scan->rs_cindex++;
		}

		/*
		 * Out of range?  If so, nothing more to look at on this page
		 */
		if (scan->rs_cindex < 0 || scan->rs_cindex >= scan->rs_ntuples)
		{
			node->tbmres = tbmres = NULL;
			continue;
		}

		/*
		 * Okay to fetch the tuple
		 */
		targoffset = scan->rs_vistuples[scan->rs_cindex];
		dp = (Page) BufferGetPage(scan->rs_cbuf);
		lp = PageGetItemId(dp, targoffset);
		Assert(ItemIdIsNormal(lp));

		scan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
		scan->rs_ctup.t_len = ItemIdGetLength(lp);
		ItemPointerSet(&scan->rs_ctup.t_self, tbmres->blockno, targoffset);

		pgstat_count_heap_fetch(scan->rs_rd);

		/*
		 * Set up the result slot to point to this tuple. Note that the slot
		 * acquires a pin on the buffer.
		 */
		ExecStoreTuple(&scan->rs_ctup,
					   slot,
					   scan->rs_cbuf,
					   false);

		/*
		 * If we are using lossy info, we have to recheck the qual conditions
		 * at every tuple.
		 */
		if (tbmres->ntuples < 0)
		{
			econtext->ecxt_scantuple = slot;
			ResetExprContext(econtext);

			if (!ExecQual(node->bitmapqualorig, econtext, false))
			{
				/* Fails recheck, so drop it and loop back for another */
				ExecClearTuple(slot);
				continue;
			}
		}

		/* OK to return this tuple */
		return slot;
	}

	/*
	 * if we get here it means we are at the end of the scan..
	 */
	return ExecClearTuple(slot);
}
Example #23
0
/*
 * ExecScanFetch -- fetch next potential tuple
 *
 * This routine is concerned with substituting a test tuple if we are
 * inside an EvalPlanQual recheck.  If we aren't, just execute
 * the access method's next-tuple routine.
 */
static inline TupleTableSlot *
ExecScanFetch(ScanState *node,
			  ExecScanAccessMtd accessMtd,
			  ExecScanRecheckMtd recheckMtd)
{
	EState	   *estate = node->ps.state;

	if (estate->es_epqTuple != NULL)
	{
		/*
		 * We are inside an EvalPlanQual recheck.  Return the test tuple if
		 * one is available, after rechecking any access-method-specific
		 * conditions.
		 */
		Index		scanrelid = ((Scan *) node->ps.plan)->scanrelid;

		if (scanrelid == 0)
		{
			TupleTableSlot *slot = node->ss_ScanTupleSlot;

			/*
			 * This is a ForeignScan or CustomScan which has pushed down a
			 * join to the remote side.  The recheck method is responsible not
			 * only for rechecking the scan/join quals but also for storing
			 * the correct tuple in the slot.
			 */
			if (!(*recheckMtd) (node, slot))
				ExecClearTuple(slot);	/* would not be returned by scan */
			return slot;
		}
		else if (estate->es_epqTupleSet[scanrelid - 1])
		{
			TupleTableSlot *slot = node->ss_ScanTupleSlot;

			/* Return empty slot if we already returned a tuple */
			if (estate->es_epqScanDone[scanrelid - 1])
				return ExecClearTuple(slot);
			/* Else mark to remember that we shouldn't return more */
			estate->es_epqScanDone[scanrelid - 1] = true;

			/* Return empty slot if we haven't got a test tuple */
			if (estate->es_epqTuple[scanrelid - 1] == NULL)
				return ExecClearTuple(slot);

			/* Store test tuple in the plan node's scan slot */
			ExecStoreTuple(estate->es_epqTuple[scanrelid - 1],
						   slot, InvalidBuffer, false);

			/* Check if it meets the access-method conditions */
			if (!(*recheckMtd) (node, slot))
				ExecClearTuple(slot);	/* would not be returned by scan */

			return slot;
		}
	}

	/*
	 * Run the node-type-specific access method function to get the next tuple
	 */
	return (*accessMtd) (node);
}
Example #24
0
/*
 * ExecSetOp for non-hashed case
 */
static TupleTableSlot *
setop_retrieve_direct(SetOpState *setopstate)
{
	SetOp	   *node = (SetOp *) setopstate->ps.plan;
	PlanState  *outerPlan;
	SetOpStatePerGroup pergroup;
	TupleTableSlot *outerslot;
	TupleTableSlot *resultTupleSlot;

	/*
	 * get state info from node
	 */
	outerPlan = outerPlanState(setopstate);
	pergroup = setopstate->pergroup;
	resultTupleSlot = setopstate->ps.ps_ResultTupleSlot;

	/*
	 * We loop retrieving groups until we find one we should return
	 */
	while (!setopstate->setop_done)
	{
		/*
		 * If we don't already have the first tuple of the new group, fetch it
		 * from the outer plan.
		 */
		if (setopstate->grp_firstTuple == NULL)
		{
			outerslot = ExecProcNode(outerPlan);
			if (!TupIsNull(outerslot))
			{
				/* Make a copy of the first input tuple */
				setopstate->grp_firstTuple = ExecCopySlotTuple(outerslot);
			}
			else
			{
				/* outer plan produced no tuples at all */
				setopstate->setop_done = true;
				return NULL;
			}
		}

		/*
		 * Store the copied first input tuple in the tuple table slot reserved
		 * for it.  The tuple will be deleted when it is cleared from the
		 * slot.
		 */
		ExecStoreTuple(setopstate->grp_firstTuple,
					   resultTupleSlot,
					   InvalidBuffer,
					   true);
		setopstate->grp_firstTuple = NULL;		/* don't keep two pointers */

		/* Initialize working state for a new input tuple group */
		initialize_counts(pergroup);

		/* Count the first input tuple */
		advance_counts(pergroup,
					   fetch_tuple_flag(setopstate, resultTupleSlot));

		/*
		 * Scan the outer plan until we exhaust it or cross a group boundary.
		 */
		for (;;)
		{
			outerslot = ExecProcNode(outerPlan);
			if (TupIsNull(outerslot))
			{
				/* no more outer-plan tuples available */
				setopstate->setop_done = true;
				break;
			}

			/*
			 * Check whether we've crossed a group boundary.
			 */
			if (!execTuplesMatch(resultTupleSlot,
								 outerslot,
								 node->numCols, node->dupColIdx,
								 setopstate->eqfunctions,
								 setopstate->tempContext))
			{
				/*
				 * Save the first input tuple of the next group.
				 */
				setopstate->grp_firstTuple = ExecCopySlotTuple(outerslot);
				break;
			}

			/* Still in same group, so count this tuple */
			advance_counts(pergroup,
						   fetch_tuple_flag(setopstate, outerslot));
		}

		/*
		 * Done scanning input tuple group.  See if we should emit any copies
		 * of result tuple, and if so return the first copy.
		 */
		set_output_count(setopstate, pergroup);

		if (setopstate->numOutput > 0)
		{
			setopstate->numOutput--;
			return resultTupleSlot;
		}
	}

	/* No more groups */
	ExecClearTuple(resultTupleSlot);
	return NULL;
}
Example #25
0
/*
 * load_consumer_state
 *
 * Read consumer state from pipeline_kafka_consumers into the given struct
 */
static void
load_consumer_state(Oid worker_id, KafkaConsumer *consumer)
{
	ScanKeyData skey[1];
	HeapTuple tup = NULL;
	HeapScanDesc scan;
	Relation consumers = open_pipeline_kafka_consumers();
	TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(consumers));
	Datum d;
	bool isnull;
	text *qualified;
	MemoryContext old;

	MemSet(consumer, 0, sizeof(KafkaConsumer));

	ScanKeyInit(&skey[0], -2, BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(worker_id));
	scan = heap_beginscan(consumers, GetTransactionSnapshot(), 1, skey);
	tup = heap_getnext(scan, ForwardScanDirection);

	if (!HeapTupleIsValid(tup))
		elog(ERROR, "kafka consumer %d not found", worker_id);

	ExecStoreTuple(tup, slot, InvalidBuffer, false);
	consumer->id = HeapTupleGetOid(tup);

	d = slot_getattr(slot, CONSUMER_ATTR_RELATION, &isnull);

	/* we don't want anything that's palloc'd to get freed when we commit */
	old = MemoryContextSwitchTo(CacheMemoryContext);

	/* target relation */
	qualified = (text *) DatumGetPointer(d);
	consumer->rel = makeRangeVarFromNameList(textToQualifiedNameList(qualified));

	/* topic */
	d = slot_getattr(slot, CONSUMER_ATTR_TOPIC, &isnull);
	consumer->topic = TextDatumGetCString(d);

	/* format */
	d = slot_getattr(slot, CONSUMER_ATTR_FORMAT, &isnull);
	consumer->format = TextDatumGetCString(d);

	/* delimiter */
	d = slot_getattr(slot, CONSUMER_ATTR_DELIMITER, &isnull);
	if (!isnull)
		consumer->delimiter = TextDatumGetCString(d);
	else
		consumer->delimiter = NULL;

	/* quote character */
	d = slot_getattr(slot, CONSUMER_ATTR_QUOTE, &isnull);
	if (!isnull)
		consumer->quote = TextDatumGetCString(d);
	else
		consumer->quote = NULL;

	/* escape character */
	d = slot_getattr(slot, CONSUMER_ATTR_ESCAPE, &isnull);
	if (!isnull)
		consumer->escape = TextDatumGetCString(d);
	else
		consumer->escape = NULL;

	/* now load all brokers */
	consumer->brokers = get_all_brokers();
	MemoryContextSwitchTo(old);

	d = slot_getattr(slot, CONSUMER_ATTR_PARALLELISM, &isnull);
	consumer->parallelism = DatumGetInt32(d);

	/* batch size */
	d = slot_getattr(slot, CONSUMER_ATTR_BATCH_SIZE, &isnull);
	consumer->batch_size = DatumGetInt32(d);

	ExecDropSingleTupleTableSlot(slot);
	heap_endscan(scan);
	heap_close(consumers, NoLock);
}
Example #26
0
/*
 * unique_key_recheck - trigger function to do a deferred uniqueness check.
 *
 * This now also does deferred exclusion-constraint checks, so the name is
 * somewhat historical.
 *
 * This is invoked as an AFTER ROW trigger for both INSERT and UPDATE,
 * for any rows recorded as potentially violating a deferrable unique
 * or exclusion constraint.
 *
 * This may be an end-of-statement check, a commit-time check, or a
 * check triggered by a SET CONSTRAINTS command.
 */
Datum
unique_key_recheck(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	const char *funcname = "unique_key_recheck";
	HeapTuple	new_row;
	ItemPointerData tmptid;
	Relation	indexRel;
	IndexInfo  *indexInfo;
	EState	   *estate;
	ExprContext *econtext;
	TupleTableSlot *slot;
	Datum		values[INDEX_MAX_KEYS];
	bool		isnull[INDEX_MAX_KEYS];

	/*
	 * Make sure this is being called as an AFTER ROW trigger.	Note:
	 * translatable error strings are shared with ri_triggers.c, so resist the
	 * temptation to fold the function name into them.
	 */
	if (!CALLED_AS_TRIGGER(fcinfo))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("function \"%s\" was not called by trigger manager",
						funcname)));

	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
		!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("function \"%s\" must be fired AFTER ROW",
						funcname)));

	/*
	 * Get the new data that was inserted/updated.
	 */
	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
		new_row = trigdata->tg_trigtuple;
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
		new_row = trigdata->tg_newtuple;
	else
	{
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("function \"%s\" must be fired for INSERT or UPDATE",
						funcname)));
		new_row = NULL;			/* keep compiler quiet */
	}

	/*
	 * If the new_row is now dead (ie, inserted and then deleted within our
	 * transaction), we can skip the check.  However, we have to be careful,
	 * because this trigger gets queued only in response to index insertions;
	 * which means it does not get queued for HOT updates.	The row we are
	 * called for might now be dead, but have a live HOT child, in which case
	 * we still need to make the check.  Therefore we have to use
	 * heap_hot_search, not just HeapTupleSatisfiesVisibility as is done in
	 * the comparable test in RI_FKey_check.
	 *
	 * This might look like just an optimization, because the index AM will
	 * make this identical test before throwing an error.  But it's actually
	 * needed for correctness, because the index AM will also throw an error
	 * if it doesn't find the index entry for the row.  If the row's dead then
	 * it's possible the index entry has also been marked dead, and even
	 * removed.
	 */
	tmptid = new_row->t_self;
	if (!heap_hot_search(&tmptid, trigdata->tg_relation, SnapshotSelf, NULL))
	{
		/*
		 * All rows in the HOT chain are dead, so skip the check.
		 */
		return PointerGetDatum(NULL);
	}

	/*
	 * Open the index, acquiring a RowExclusiveLock, just as if we were going
	 * to update it.  (This protects against possible changes of the index
	 * schema, not against concurrent updates.)
	 */
	indexRel = index_open(trigdata->tg_trigger->tgconstrindid,
						  RowExclusiveLock);
	indexInfo = BuildIndexInfo(indexRel);

	/*
	 * The heap tuple must be put into a slot for FormIndexDatum.
	 */
	slot = MakeSingleTupleTableSlot(RelationGetDescr(trigdata->tg_relation));

	ExecStoreTuple(new_row, slot, InvalidBuffer, false);

	/*
	 * Typically the index won't have expressions, but if it does we need an
	 * EState to evaluate them.  We need it for exclusion constraints too,
	 * even if they are just on simple columns.
	 */
	if (indexInfo->ii_Expressions != NIL ||
		indexInfo->ii_ExclusionOps != NULL)
	{
		estate = CreateExecutorState();
		econtext = GetPerTupleExprContext(estate);
		econtext->ecxt_scantuple = slot;
	}
	else
		estate = NULL;

	/*
	 * Form the index values and isnull flags for the index entry that we need
	 * to check.
	 *
	 * Note: if the index uses functions that are not as immutable as they are
	 * supposed to be, this could produce an index tuple different from the
	 * original.  The index AM can catch such errors by verifying that it
	 * finds a matching index entry with the tuple's TID.  For exclusion
	 * constraints we check this in check_exclusion_constraint().
	 */
	FormIndexDatum(indexInfo, slot, estate, values, isnull);

	/*
	 * Now do the appropriate check.
	 */
	if (indexInfo->ii_ExclusionOps == NULL)
	{
		/*
		 * Note: this is not a real insert; it is a check that the index entry
		 * that has already been inserted is unique.
		 */
		index_insert(indexRel, values, isnull, &(new_row->t_self),
					 trigdata->tg_relation, UNIQUE_CHECK_EXISTING);
	}
	else
	{
		/*
		 * For exclusion constraints we just do the normal check, but now it's
		 * okay to throw error.
		 */
		check_exclusion_constraint(trigdata->tg_relation, indexRel, indexInfo,
								   &(new_row->t_self), values, isnull,
								   estate, false, false);
	}

	/*
	 * If that worked, then this index entry is unique or non-excluded, and we
	 * are done.
	 */
	if (estate != NULL)
		FreeExecutorState(estate);

	ExecDropSingleTupleTableSlot(slot);

	index_close(indexRel, RowExclusiveLock);

	return PointerGetDatum(NULL);
}
Example #27
0
/* ----------------------------------------------------------------
 *		ExecMaterial
 *
 *		As long as we are at the end of the data collected in the tuplestore,
 *		we collect one new row from the subplan on each call, and stash it
 *		aside in the tuplestore before returning it.  The tuplestore is
 *		only read if we are asked to scan backwards, rescan, or mark/restore.
 *
 * ----------------------------------------------------------------
 */
TupleTableSlot *				/* result tuple from subplan */
ExecMaterial(MaterialState *node)
{
	EState	   *estate;
	ScanDirection dir;
	bool		forward;
	Tuplestorestate *tuplestorestate;
	HeapTuple	heapTuple = NULL;
	bool		should_free = false;
	bool		eof_tuplestore;
	TupleTableSlot *slot;

	/*
	 * get state info from node
	 */
	estate = node->ss.ps.state;
	dir = estate->es_direction;
	forward = ScanDirectionIsForward(dir);
	tuplestorestate = (Tuplestorestate *) node->tuplestorestate;

	/*
	 * If first time through, and we need a tuplestore, initialize it.
	 */
	if (tuplestorestate == NULL && node->randomAccess)
	{
		tuplestorestate = tuplestore_begin_heap(true, false, work_mem);

		node->tuplestorestate = (void *) tuplestorestate;
	}

	/*
	 * If we are not at the end of the tuplestore, or are going backwards, try
	 * to fetch a tuple from tuplestore.
	 */
	eof_tuplestore = (tuplestorestate == NULL) ||
		tuplestore_ateof(tuplestorestate);

	if (!forward && eof_tuplestore)
	{
		if (!node->eof_underlying)
		{
			/*
			 * When reversing direction at tuplestore EOF, the first
			 * getheaptuple call will fetch the last-added tuple; but we want
			 * to return the one before that, if possible. So do an extra
			 * fetch.
			 */
			heapTuple = tuplestore_getheaptuple(tuplestorestate,
												forward,
												&should_free);
			if (heapTuple == NULL)
				return NULL;	/* the tuplestore must be empty */
			if (should_free)
				heap_freetuple(heapTuple);
		}
		eof_tuplestore = false;
	}

	if (!eof_tuplestore)
	{
		heapTuple = tuplestore_getheaptuple(tuplestorestate,
											forward,
											&should_free);
		if (heapTuple == NULL && forward)
			eof_tuplestore = true;
	}

	/*
	 * If necessary, try to fetch another row from the subplan.
	 *
	 * Note: the eof_underlying state variable exists to short-circuit further
	 * subplan calls.  It's not optional, unfortunately, because some plan
	 * node types are not robust about being called again when they've already
	 * returned NULL.
	 */
	if (eof_tuplestore && !node->eof_underlying)
	{
		PlanState  *outerNode;
		TupleTableSlot *outerslot;

		/*
		 * We can only get here with forward==true, so no need to worry about
		 * which direction the subplan will go.
		 */
		outerNode = outerPlanState(node);
		outerslot = ExecProcNode(outerNode);
		if (TupIsNull(outerslot))
		{
			node->eof_underlying = true;
			return NULL;
		}
		heapTuple = ExecFetchSlotTuple(outerslot);
		should_free = false;

		/*
		 * Append returned tuple to tuplestore, too.  NOTE: because the
		 * tuplestore is certainly in EOF state, its read position will move
		 * forward over the added tuple.  This is what we want.
		 */
		if (tuplestorestate)
			tuplestore_puttuple(tuplestorestate, (void *) heapTuple);
	}

	/*
	 * Return the obtained tuple, if any.
	 */
	slot = (TupleTableSlot *) node->ss.ps.ps_ResultTupleSlot;
	if (heapTuple)
		return ExecStoreTuple(heapTuple, slot, InvalidBuffer, should_free);
	else
		return ExecClearTuple(slot);
}
Example #28
0
/*
 * CatalogIndexInsert - insert index entries for one catalog tuple
 *
 * This should be called for each inserted or updated catalog tuple.
 *
 * This is effectively a cut-down version of ExecInsertIndexTuples.
 */
void
CatalogIndexInsert(CatalogIndexState indstate, HeapTuple heapTuple)
{
	int			i;
	int			numIndexes;
	RelationPtr relationDescs;
	Relation	heapRelation;
	TupleTableSlot *slot;
	IndexInfo **indexInfoArray;
	Datum		values[INDEX_MAX_KEYS];
	bool		isnull[INDEX_MAX_KEYS];

	/* HOT update does not require index inserts */
	if (HeapTupleIsHeapOnly(heapTuple))
		return;

	/*
	 * Get information from the state structure.  Fall out if nothing to do.
	 */
	numIndexes = indstate->ri_NumIndices;
	if (numIndexes == 0)
		return;
	relationDescs = indstate->ri_IndexRelationDescs;
	indexInfoArray = indstate->ri_IndexRelationInfo;
	heapRelation = indstate->ri_RelationDesc;

	/* Need a slot to hold the tuple being examined */
	slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation));
	ExecStoreTuple(heapTuple, slot, InvalidBuffer, false);

	/*
	 * for each index, form and insert the index tuple
	 */
	for (i = 0; i < numIndexes; i++)
	{
		IndexInfo  *indexInfo;

		indexInfo = indexInfoArray[i];

		/* If the index is marked as read-only, ignore it */
		if (!indexInfo->ii_ReadyForInserts)
			continue;

		/*
		 * Expressional and partial indexes on system catalogs are not
		 * supported, nor exclusion constraints, nor deferred uniqueness
		 */
		Assert(indexInfo->ii_Expressions == NIL);
		Assert(indexInfo->ii_Predicate == NIL);
		Assert(indexInfo->ii_ExclusionOps == NULL);
		Assert(relationDescs[i]->rd_index->indimmediate);

		/*
		 * FormIndexDatum fills in its values and isnull parameters with the
		 * appropriate values for the column(s) of the index.
		 */
		FormIndexDatum(indexInfo,
					   slot,
					   NULL,	/* no expression eval to do */
					   values,
					   isnull);

		/*
		 * The index AM does the rest.
		 */
		index_insert(relationDescs[i],	/* index relation */
					 values,	/* array of index Datums */
					 isnull,	/* is-null flags */
					 &(heapTuple->t_self),		/* tid of heap tuple */
					 heapRelation,
					 relationDescs[i]->rd_index->indisunique ?
					 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO);
	}

	ExecDropSingleTupleTableSlot(slot);
}
Example #29
0
/* ----------------------------------------------------------------
 *		IndexNext
 *
 *		Retrieve a tuple from the IndexScan node's currentRelation
 *		using the index specified in the IndexScanState information.
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
IndexNext(IndexScanState *node)
{
	EState	   *estate;
	ExprContext *econtext;
	ScanDirection direction;
	IndexScanDesc scandesc;
	HeapTuple	tuple;
	TupleTableSlot *slot;

	/*
	 * extract necessary information from index scan node
	 */
	estate = node->ss.ps.state;
	direction = estate->es_direction;
	/* flip direction if this is an overall backward scan */
	if (ScanDirectionIsBackward(((IndexScan *) node->ss.ps.plan)->indexorderdir))
	{
		if (ScanDirectionIsForward(direction))
			direction = BackwardScanDirection;
		else if (ScanDirectionIsBackward(direction))
			direction = ForwardScanDirection;
	}
	scandesc = node->iss_ScanDesc;
	econtext = node->ss.ps.ps_ExprContext;
	slot = node->ss.ss_ScanTupleSlot;

	/*
	 * ok, now that we have what we need, fetch the next tuple.
	 */
	while ((tuple = index_getnext(scandesc, direction)) != NULL)
	{
		/*
		 * Store the scanned tuple in the scan tuple slot of the scan state.
		 * Note: we pass 'false' because tuples returned by amgetnext are
		 * pointers onto disk pages and must not be pfree()'d.
		 */
		ExecStoreTuple(tuple,	/* tuple to store */
					   slot,	/* slot to store in */
					   scandesc->xs_cbuf,		/* buffer containing tuple */
					   false);	/* don't pfree */

		/*
		 * If the index was lossy, we have to recheck the index quals using
		 * the real tuple.
		 */
		if (scandesc->xs_recheck)
		{
			econtext->ecxt_scantuple = slot;
			ResetExprContext(econtext);
			if (!ExecQual(node->indexqualorig, econtext, false))
				continue;		/* nope, so ask index for another one */
		}

		return slot;
	}

	/*
	 * if we get here it means the index scan failed so we are at the end of
	 * the scan..
	 */
	return ExecClearTuple(slot);
}
Example #30
0
/* ----------------------------------------------------------------
 *		BitmapHeapNext
 *
 *		Retrieve next tuple from the BitmapHeapScan node's currentRelation
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
BitmapHeapNext(BitmapHeapScanState *node)
{
	ExprContext *econtext;
	HeapScanDesc scan;
	TIDBitmap  *tbm;
	TBMIterator *tbmiterator;
	TBMIterateResult *tbmres;
	TBMIterator *prefetch_iterator;
	OffsetNumber targoffset;
	TupleTableSlot *slot;

	/*
	 * extract necessary information from index scan node
	 */
	econtext = node->ss.ps.ps_ExprContext;
	slot = node->ss.ss_ScanTupleSlot;
	scan = node->ss.ss_currentScanDesc;
	tbm = node->tbm;
	tbmiterator = node->tbmiterator;
	tbmres = node->tbmres;
	prefetch_iterator = node->prefetch_iterator;

	/*
	 * If we haven't yet performed the underlying index scan, do it, and begin
	 * the iteration over the bitmap.
	 *
	 * For prefetching, we use *two* iterators, one for the pages we are
	 * actually scanning and another that runs ahead of the first for
	 * prefetching.  node->prefetch_pages tracks exactly how many pages ahead
	 * the prefetch iterator is.  Also, node->prefetch_target tracks the
	 * desired prefetch distance, which starts small and increases up to the
	 * GUC-controlled maximum, target_prefetch_pages.  This is to avoid doing
	 * a lot of prefetching in a scan that stops after a few tuples because of
	 * a LIMIT.
	 */
	if (tbm == NULL)
	{
		tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));

		if (!tbm || !IsA(tbm, TIDBitmap))
			elog(ERROR, "unrecognized result from subplan");

		node->tbm = tbm;
		node->tbmiterator = tbmiterator = tbm_begin_iterate(tbm);
		node->tbmres = tbmres = NULL;

#ifdef USE_PREFETCH
		if (target_prefetch_pages > 0)
		{
			node->prefetch_iterator = prefetch_iterator = tbm_begin_iterate(tbm);
			node->prefetch_pages = 0;
			node->prefetch_target = -1;
		}
#endif   /* USE_PREFETCH */
	}

	for (;;)
	{
		Page		dp;
		ItemId		lp;

		/*
		 * Get next page of results if needed
		 */
		if (tbmres == NULL)
		{
			node->tbmres = tbmres = tbm_iterate(tbmiterator);
			if (tbmres == NULL)
			{
				/* no more entries in the bitmap */
				break;
			}

#ifdef USE_PREFETCH
			if (node->prefetch_pages > 0)
			{
				/* The main iterator has closed the distance by one page */
				node->prefetch_pages--;
			}
			else if (prefetch_iterator)
			{
				/* Do not let the prefetch iterator get behind the main one */
				TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);

				if (tbmpre == NULL || tbmpre->blockno != tbmres->blockno)
					elog(ERROR, "prefetch and main iterators are out of sync");
			}
#endif   /* USE_PREFETCH */

			/*
			 * Ignore any claimed entries past what we think is the end of the
			 * relation.  (This is probably not necessary given that we got at
			 * least AccessShareLock on the table before performing any of the
			 * indexscans, but let's be safe.)
			 */
			if (tbmres->blockno >= scan->rs_nblocks)
			{
				node->tbmres = tbmres = NULL;
				continue;
			}

			/*
			 * Fetch the current heap page and identify candidate tuples.
			 */
			bitgetpage(scan, tbmres);

			/*
			 * Set rs_cindex to first slot to examine
			 */
			scan->rs_cindex = 0;

#ifdef USE_PREFETCH

			/*
			 * Increase prefetch target if it's not yet at the max.  Note that
			 * we will increase it to zero after fetching the very first
			 * page/tuple, then to one after the second tuple is fetched, then
			 * it doubles as later pages are fetched.
			 */
			if (node->prefetch_target >= target_prefetch_pages)
				 /* don't increase any further */ ;
			else if (node->prefetch_target >= target_prefetch_pages / 2)
				node->prefetch_target = target_prefetch_pages;
			else if (node->prefetch_target > 0)
				node->prefetch_target *= 2;
			else
				node->prefetch_target++;
#endif   /* USE_PREFETCH */
		}
		else
		{
			/*
			 * Continuing in previously obtained page; advance rs_cindex
			 */
			scan->rs_cindex++;

#ifdef USE_PREFETCH

			/*
			 * Try to prefetch at least a few pages even before we get to the
			 * second page if we don't stop reading after the first tuple.
			 */
			if (node->prefetch_target < target_prefetch_pages)
				node->prefetch_target++;
#endif   /* USE_PREFETCH */
		}

		/*
		 * Out of range?  If so, nothing more to look at on this page
		 */
		if (scan->rs_cindex < 0 || scan->rs_cindex >= scan->rs_ntuples)
		{
			node->tbmres = tbmres = NULL;
			continue;
		}

#ifdef USE_PREFETCH

		/*
		 * We issue prefetch requests *after* fetching the current page to try
		 * to avoid having prefetching interfere with the main I/O. Also, this
		 * should happen only when we have determined there is still something
		 * to do on the current page, else we may uselessly prefetch the same
		 * page we are just about to request for real.
		 */
		if (prefetch_iterator)
		{
			while (node->prefetch_pages < node->prefetch_target)
			{
				TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);

				if (tbmpre == NULL)
				{
					/* No more pages to prefetch */
					tbm_end_iterate(prefetch_iterator);
					node->prefetch_iterator = prefetch_iterator = NULL;
					break;
				}
				node->prefetch_pages++;
				PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
			}
		}
#endif   /* USE_PREFETCH */

		/*
		 * Okay to fetch the tuple
		 */
		targoffset = scan->rs_vistuples[scan->rs_cindex];
		dp = (Page) BufferGetPage(scan->rs_cbuf);
		lp = PageGetItemId(dp, targoffset);
		Assert(ItemIdIsNormal(lp));

		scan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
		scan->rs_ctup.t_len = ItemIdGetLength(lp);
		ItemPointerSet(&scan->rs_ctup.t_self, tbmres->blockno, targoffset);

		pgstat_count_heap_fetch(scan->rs_rd);

		/*
		 * Set up the result slot to point to this tuple. Note that the slot
		 * acquires a pin on the buffer.
		 */
		ExecStoreTuple(&scan->rs_ctup,
					   slot,
					   scan->rs_cbuf,
					   false);

		/*
		 * If we are using lossy info, we have to recheck the qual conditions
		 * at every tuple.
		 */
		if (tbmres->recheck)
		{
			econtext->ecxt_scantuple = slot;
			ResetExprContext(econtext);

			if (!ExecQual(node->bitmapqualorig, econtext, false))
			{
				/* Fails recheck, so drop it and loop back for another */
				ExecClearTuple(slot);
				continue;
			}
		}

		/* OK to return this tuple */
		return slot;
	}

	/*
	 * if we get here it means we are at the end of the scan..
	 */
	return ExecClearTuple(slot);
}