Function table_beginscan

src/include/access/tableam.h:1018–1026

* Start a scan of `rel`. Returned tuples pass a visibility test of * `snapshot`, and if nkeys != 0, the results are filtered by those scan keys. */

 * `snapshot`, and if nkeys != 0, the results are filtered by those scan keys.
 */
static inline TableScanDesc
table_beginscan(Relation rel, Snapshot snapshot,
				int nkeys, struct ScanKeyData *key)
{
	uint32		flags = SO_TYPE_SEQSCAN |
	SO_ALLOW_STRAT | SO_ALLOW_SYNC | SO_ALLOW_PAGEMODE;

	return rel->rd_tableam->scan_begin(rel, snapshot, nkeys, key, NULL, flags);
}

/*
 * GPDB: Like table_beginscan(), but first attempt to create a