Hello, Alexander! Please consider changes to the patch:
вт, 17 июл. 2018 г. в 16:59, Alexander Turenko <
alexander.turenko@xxxxxxxxxxxxx>:
Hi Nikita!Fixed:
Please, consider comments below.
WBR, Alexander Turenko.
On Mon, Jul 02, 2018 at 03:11:40PM +0300, N.Tatunov wrote:
To optimize the select-subquery tarantool uses
subquery flattening function which is only used
with respect to some restrictions. One of them
was implemented improperly.
Be certain: 'some restriction' and just 'improperly' are not good
problem descriptions.
I would use wording like the following.
When a subquery is a compound select the subquery flattening
optimization verify whether the ORDER BY clause presents, but only for
the last subquery component. The commit fixes that to verify all
subquery components.
In case of ORDER BY in non-last component of a compound select the
error should be raised. Accepting of such subqueries for the
flattening optimization prevents the error to be raised afterwards.
Instead it stuck into assertion violation inside flattenSubquery (see
the issue).
I checked sqlite3 check-in 8000d230 (it is immediate predecessor of
c9104b59 where the flattening optimization seems to be changed, but
tarantool didn't updated with that check-in). It has the assert, but has
no a change like yours, and correctly shows the following error:
Error: ORDER BY clause should come after UNION ALL not before
Why it is so?
+test:do_catchsql_test(
+ "subquery-9.3",
+ [[
+ SELECT * FROM (SELECT * FROM table1 ORDER BY 1 UNION All
+ SELECT * FROM table1 UNION All
+ SELECT * FROM table1);
All -> ALL