Sergey Vojtovich <notifications@github.com> writes:
ATTN @dr-m, @andrelkin, @SachinSetiya, @knielsen
So IIUC, this is about incorrect usage of ha_truncate() in rpl_slave_state::truncate_state_table(). This is used only for SET GLOBAL gtid_slave_pos = "..." when all slave threads are stopped and nothing else is accessing the gtid_pos table. So it's fine to use ha_truncate() if that can be done easily (and correctly). But it would also be fine just to loop and delete all rows one by one in a normal transaction, if that is simpler. gtid_slave_pos is a small table, there are normally only a few rows per active replication domain. I'm not myself very familiar with details of metadata locking etc. around ha_truncate(). But looking at the code now, I don't understand why it only truncates one table? If --gtid-pos-auto-engines is in effect, there could be multiple tables... shouldn't they all be cleared when setting the gtid_slave_pos variable? If so, maybe the delete-rows-one-by-one approach is in any case preferable over ha_truncate, since it can then be done transactionally, to not leave an inconsistent gtid_slave_pos state if one truncate fails and another succeeds? Hope this helps, - Kristian.