Function table_tuple_fetch_row_version

src/include/access/tableam.h:1488–1503

* Fetch tuple at `tid` into `slot`, after doing a visibility test according to * `snapshot`. If a tuple was found and passed the visibility test, returns * true, false otherwise. * * See table_index_fetch_tuple's comment about what the difference between * these functions is. It is correct to use this function outside of index * entry->table tuple lookups. */

 * entry->table tuple lookups.
 */
static inline bool
table_tuple_fetch_row_version(Relation rel,
							  ItemPointer tid,
							  Snapshot snapshot,
							  TupleTableSlot *slot)
{
	/*
	 * We don't expect direct calls to table_tuple_fetch_row_version with
	 * valid CheckXidAlive for catalog or regular tables.  See detailed
	 * comments in xact.c where these variables are declared.
	 */
	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
		elog(ERROR, "unexpected table_tuple_fetch_row_version call during logical decoding");

	return rel->rd_tableam->tuple_fetch_row_version(rel, tid, snapshot, slot);
}

/*
 * Verify that `tid` is a potentially valid tuple identifier. That doesn't