Function transformPartitionRangeBounds

src/backend/parser/parse_utilcmd.c:5363–5479

* transformPartitionRangeBounds * This converts the expressions for range partition bounds from the raw * grammar representation to PartitionRangeDatum structs */

 *		grammar representation to PartitionRangeDatum structs
 */
static List *
transformPartitionRangeBounds(ParseState *pstate, List *blist,
							  Relation parent, PartitionKey key)
{
	List	   *result = NIL;
	List	   *partexprs = get_partition_exprs(key);
	ListCell   *lc;
	int			i,
				j;

	i = j = 0;
	foreach(lc, blist)
	{
		Node	   *expr = lfirst(lc);
		PartitionRangeDatum *prd = NULL;

		/*
		 * Infinite range bounds -- "minvalue" and "maxvalue" -- get passed in
		 * as ColumnRefs.
		 */
		if (IsA(expr, ColumnRef))
		{
			ColumnRef  *cref = (ColumnRef *) expr;
			char	   *cname = NULL;

			/*
			 * There should be a single field named either "minvalue" or
			 * "maxvalue".
			 */
			if (list_length(cref->fields) == 1 &&
				IsA(linitial(cref->fields), String))
				cname = strVal(linitial(cref->fields));

			if (cname == NULL)
			{
				/*
				 * ColumnRef is not in the desired single-field-name form. For
				 * consistency between all partition strategies, let the
				 * expression transformation report any errors rather than
				 * doing it ourselves.
				 */
			}
			else if (strcmp("minvalue", cname) == 0)
			{
				prd = makeNode(PartitionRangeDatum);
				prd->kind = PARTITION_RANGE_DATUM_MINVALUE;
				prd->value = NULL;
			}
			else if (strcmp("maxvalue", cname) == 0)
			{
				prd = makeNode(PartitionRangeDatum);
				prd->kind = PARTITION_RANGE_DATUM_MAXVALUE;
				prd->value = NULL;
			}
		}
		else if (IsA(expr, PartitionRangeDatum))
		{
			/*