Idle transaction timeouts kills connections rather than transactions

Note: Possibly it's just a documentation issue; if it is so, please switch the category.

If idle_transaction_timeout or its siblings are set, and the timeout is exceeded, not only the open transaction closes, but the entire session (connection) gets dropped.

MDEV-11418 (KILL IDLE TRANSACTIONS) only speaks about killing transactions; documentation is even less verbose in this regard, but it also only mentions transactions; finally, the tests in pull request, although they enable reconnect and thus apparently expect the connection to be lost, do not show it specifically.

Killing the entire session seems to be excessive for the declared goal, but if it has to be so, please document it properly. The difference in semantics is similar to KILL <id> vs KILL QUERY <id>, and it is essential for setting up proper workflow and tuning applications which might be affected by the timeouts.

--connect (con1,localhost,root,,)

set idle_transaction_timeout= 2;

--enable_reconnect

BEGIN;

SELECT CONNECTION_ID();

--sleep 3

--error 2006,2013

SELECT "Dead";

SELECT CONNECTION_ID();

--disconnect con1

connect  con1,localhost,root,,;

set idle_transaction_timeout= 2;

BEGIN;

SELECT CONNECTION_ID();

CONNECTION_ID()

5

SELECT "Dead";

Got one of the listed errors

SELECT CONNECTION_ID();

CONNECTION_ID()

6

disconnect con1;