Function resolve_column_ref

src/pl/plpgsql/src/pl_comp.c:1197–1355

* resolve_column_ref attempt to resolve a ColumnRef as a plpgsql var * * Returns the translated node structure, or NULL if name not found * * error_if_no_field tells whether to throw error or quietly return NULL if * we are able to match a record/row name but don't find a field name match. */

 * we are able to match a record/row name but don't find a field name match.
 */
static Node *
resolve_column_ref(ParseState *pstate, PLpgSQL_expr *expr,
				   ColumnRef *cref, bool error_if_no_field)
{
	PLpgSQL_execstate *estate;
	PLpgSQL_nsitem *nse;
	const char *name1;
	const char *name2 = NULL;
	const char *name3 = NULL;
	const char *colname = NULL;
	int			nnames;
	int			nnames_scalar = 0;
	int			nnames_wholerow = 0;
	int			nnames_field = 0;

	/*
	 * We use the function's current estate to resolve parameter data types.
	 * This is really pretty bogus because there is no provision for updating
	 * plans when those types change ...
	 */
	estate = expr->func->cur_estate;

	/*----------
	 * The allowed syntaxes are:
	 *
	 * A		Scalar variable reference, or whole-row record reference.
	 * A.B		Qualified scalar or whole-row reference, or field reference.
	 * A.B.C	Qualified record field reference.
	 * A.*		Whole-row record reference.
	 * A.B.*	Qualified whole-row record reference.
	 *----------
	 */
	switch (list_length(cref->fields))
	{
		case 1:
			{
				Node	   *field1 = (Node *) linitial(cref->fields);

				Assert(IsA(field1, String));
				name1 = strVal(field1);
				nnames_scalar = 1;
				nnames_wholerow = 1;
				break;
			}
		case 2:
			{
				Node	   *field1 = (Node *) linitial(cref->fields);
				Node	   *field2 = (Node *) lsecond(cref->fields);

				Assert(IsA(field1, String));
				name1 = strVal(field1);

				/* Whole-row reference? */
				if (IsA(field2, A_Star))
				{
					/* Set name2 to prevent matches to scalar variables */
					name2 = "*";
					nnames_wholerow = 1;