Function initNextIndexToScan

src/backend/executor/execDynamicIndexes.c:227–256

* This function initializes a part and returns true if a new index has been prepared for scanning. */

 * This function initializes a part and returns true if a new index has been prepared for scanning.
 */
static bool
initNextIndexToScan(DynamicIndexScanState *node)
{
	EState	   *estate = node->ss.ps.state;

	/* Load new index when the scanning of the previous index is done. */
	if (node->scan_state == SCAN_INIT ||
		node->scan_state == SCAN_DONE)
	{
		/* This is the oid of a partition of the table (*not* index) */
		Oid			tableOid;

		if (++node->whichPart < node->nOids)
			tableOid = node->partOids[node->whichPart];
		else
			return false;

		/* Collect number of partitions scanned in EXPLAIN ANALYZE */
		if (node->ss.ps.instrument)
			node->ss.ps.instrument->numPartScanned++;

		endCurrentIndexScan(node);

		beginCurrentIndexScan(node, estate, tableOid);

		node->scan_state = SCAN_SCAN;
	}

	return true;
}

TupleTableSlot *
ExecNextDynamicIndexScan(DynamicIndexScanState *node)