hi Jeremy,
I can not give a test case because I have changed the way of retrying
transaction in mysql-5.5.30 and then found this problem. The mysql-5.5.30 SQL
thread's original way that retry failed events group(or a transaction) is
droping the failed log-event object, then reading group's log events from BEGIN
in relay log and applying their objects one by one again.for the log-event
objects is new, the process of retry can get the same result as last time.
But in parallel replication of dingqi's patch the retry-way is changed. It
reads in all events of a group and build a list of log-event objects in a time
, then call log events' do_apply_event function from the event-object list head
to tail. If there is some error happened, the retry-way is calling log events'
do_apply_event function from the event-object list head again. so a log event
object could do do_apply_event() twice. I imitated this process in
mysql-5.5.30, made a log event object do do_apply_event() twice when it first
time return nozero. then I find this problem that a
Rows_log_event::do_apply_event() could call twice but return different
results(first time is nozero, while second is zero). I also find the reason why
the second time return zero is m_curr_row==m_rows_end in the Rows_log_event
object. Does it need to set m_curr_row back to its original value before return
from Rows_log_event::do_apply_event().
Regards,
Rao
2013-07-16
nanyi607rao
Hi,
Do you have a test case (or sequence of SQL statements you could provide in
email)? Your email is a bit hard to follow, but this sounds interesting.
Regards,
Jeremy
On Thu, Jul 11, 2013 at 11:51 PM, nanyi607rao <nanyi607...@gmail.com> wrote:
hi,
In order to test "retry_transaction" in function
execute_single_transaction(), I change Relay_log_pos to make SQL thread insert
Duplicate entry, but I find it successed and do not report error!
so I debug the function execute_single_transaction() and find the reason : at
first time, the insert Rows_log_event::do_apply_event() return 121, that means
insert fails. But when retry the insert Rows_log_event::do_apply_event(),it
return 0, that means insert success! it seems the
Rows_log_event::do_apply_event() do twice, but return different results. how
this happened? is it a bug of Rows_log_event::do_apply_event() ?
By the way, I do this test in mysql-5.5.30, do mariaDB has the some problem?
2013-07-12
nanyi607rao
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