Function transformGroupingSet

src/backend/parser/parse_clause.c:2614–2678

* Transform a grouping set and (recursively) its content. * * The grouping set might be a GROUPING SETS node with other grouping sets * inside it, but SETS within SETS have already been flattened out before * reaching here. * * Returns the transformed node, which now contains SIMPLE nodes with lists * of ressortgrouprefs rather than expressions. * * flatresult reference to flat list of So

 * toplevel		false if within any grouping set
 */
static Node *
transformGroupingSet(List **flatresult,
					 ParseState *pstate, GroupingSet *gset,
					 List **targetlist, List *sortClause,
					 ParseExprKind exprKind, bool useSQL99, bool toplevel)
{
	ListCell   *gl;
	List	   *content = NIL;

	Assert(toplevel || gset->kind != GROUPING_SET_SETS);

	foreach(gl, gset->content)
	{
		Node	   *n = lfirst(gl);

		if (IsA(n, List))
		{
			List	   *l = transformGroupClauseList(flatresult,
													 pstate, (List *) n,
													 targetlist, sortClause,
													 exprKind, useSQL99, false);

			content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
													   l,
													   exprLocation(n)));
		}
		else if (IsA(n, GroupingSet))
		{
			GroupingSet *gset2 = (GroupingSet *) lfirst(gl);

			content = lappend(content, transformGroupingSet(flatresult,
															pstate, gset2,
															targetlist, sortClause,
															exprKind, useSQL99, false));
		}
		else
		{
			Index		ref = transformGroupClauseExpr(flatresult,
													   NULL,
													   pstate,
													   n,
													   targetlist,
													   sortClause,
													   exprKind,
													   useSQL99,
													   false);

			content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
													   list_make1_int(ref),
													   exprLocation(n)));
		}
	}

	/* Arbitrarily cap the size of CUBE, which has exponential growth */
	if (gset->kind == GROUPING_SET_CUBE)
	{
		if (list_length(content) > 12)
			ereport(ERROR,