Plase, = make up a list of tests to be enabled after multi-directional
iterators are introduced. Don=E2=80=99t fix tests which fail = now, simply comment
them. Finally, add a few simple tests = verifying that different sorting
orders are not supported = now.

I did as you say. Added list of tests as a comment to = #3309.
But I would = like to know, why commenting tests & making a list
of them is better than change = tests & comment old expected results?
The main advantage is that one can not ignore/miss tests, = which
would fail = after #3309 is done.

Firstly, they won=E2=80=99t automatically start to = fail, since check is SQL

code won=E2=80=99t disappear itself. = Secondly, such approach allows to

significantly reduce efforts = to turn tests on/off after/before fixes.

+    -- Tests are commented because of the = reason described in
+    -- NOTE at the beginning of the = file.
+ =    -- <begin>
+    --local data =3D {
+    -- =    {limit=3D0, offset=3D4, orderby=3D"+b,+a"},
+    -- =    {limit=3D0, offset=3D5, orderby=3D"+b,+a"},
+    -- =    {limit=3D0, offset=3D6, orderby=3D"+b,+a"},
+    -- =    {limit=3D0, offset=3D9, orderby=3D"+b,+a"},
+    -- =    {limit=3D0, offset=3D0, orderby=3D"+b,+a"},
+    -- =    {limit=3D0, offset=3D1, orderby=3D"+b,+a"},
+    -- =    {limit=3D7, offset=3D4, orderby=3D"+b,+a"},
+    -- =    {limit=3D7, offset=3D9, orderby=3D"+b,+a=E2=80=9D},

These = first tests come with the same sorting orders,

can we avoid = commenting them?

+    --    {limit=3D0, = offset=3D4, orderby=3D"+b DESC,+a"},
+    --    {limit=3D0, = offset=3D5, orderby=3D"+b DESC,+a"},
+    --    {limit=3D0, = offset=3D6, orderby=3D"+b DESC,+a"},
+    --    {limit=3D0, = offset=3D9, orderby=3D"+b DESC,+a"},
+    --    {limit=3D0, = offset=3D0, orderby=3D"+b DESC,+a"},
+    --    {limit=3D0, = offset=3D1, orderby=3D"+b DESC,+a"},
+    --    {limit=3D7, = offset=3D4, orderby=3D"+b DESC,+a"},
+    --    {limit=3D7, = offset=3D9, orderby=3D"+b DESC,+a"},

+void
+sql_expr_check_sort_orders(struct= Parse *parse,
+ =    const struct = ExprList *expr_list)
+{
+ if(expr_list = =3D=3D NULL)
+ return;
+ enum sort_order reference_order =3D = expr_list->a[0].sort_order;
+ for (int i =3D 1; i < expr_list->nExpr; i++) = {
+ assert(expr_list->a[i].sort_order !=3D = SORT_ORDER_UNDEF);
+ = if = (expr_list->a[i].sort_order !=3D reference_order) {
+ = diag_set(ClientError, ER_UNSUPPORTED, "ORDER BY",
+ = "different sorting = orders=E2=80=9D);

Different sorting orders and LIMIT clause at the = same time OR

=E2=80=9CORDER BY with LIMIT=E2=80=9D, = =E2=80=9Cdifferent sorting orders=E2=80=9D.