Function ExpandAllTables

src/backend/parser/parse_target.c:1292–1330

* ExpandAllTables() * Transforms '*' (in the target list) into a list of targetlist entries. * * tlist entries are generated for each relation visible for unqualified * column name access. We do not consider qualified-name-only entries because * that would include input tables of aliasless JOINs, NEW/OLD pseudo-entries, * etc. * * The referenced relations/columns are marked as requiring

 * The referenced relations/columns are marked as requiring SELECT access.
 */
static List *
ExpandAllTables(ParseState *pstate, int location)
{
	List	   *target = NIL;
	bool		found_table = false;
	ListCell   *l;

	foreach(l, pstate->p_namespace)
	{
		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(l);

		/* Ignore table-only items */
		if (!nsitem->p_cols_visible)
			continue;
		/* Should not have any lateral-only items when parsing targetlist */
		Assert(!nsitem->p_lateral_only);
		/* Remember we found a p_cols_visible item */
		found_table = true;

		target = list_concat(target,
							 expandNSItemAttrs(pstate,
											   nsitem,
											   0,
											   location));
	}

	/*
	 * Check for "SELECT *;".  We do it this way, rather than checking for
	 * target == NIL, because we want to allow SELECT * FROM a zero_column
	 * table.
	 */
	if (!found_table)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("SELECT * with no tables specified is not valid"),
				 parser_errposition(pstate, location)));

	return target;
}

/*
 * ExpandIndirectionStar()