Add possibility to set serverId as gh-ost option

[cypissa]

Signed-off-by: Cyprian Nosek [email protected]

In a case where I want to run several gh-ost processes in parallel it seems to be not possible due to all of the processes show up with the same serverId: 99999 (it's const in the code).

Possibility to pass serverId as an option with command line (with default set to 99999) would solve the problem.

The change adds optional -replica-server-id flag where it's possible to set serverId.

[shlomi-noach]

Thank you. This should ideally be submitted on https://github.com/siddontang/go-mysql, and of course we can diverge from that library a bit.

Having said that, we've been running multiple concurrent migrations without problem. What is the error you saw?

[shlomi-noach]

Very nicely done, thank you!

[cypissa]

Hi, thanks for the quick reply. The error I meet is as follows:

INFO StreamEvents encountered unexpected error: ERROR 1236 (HY000): A slave with the same server_uuid/server_id as this slave has connected to the master; the first event 'mysql-bin.000004' at 4, the last event read from '/var/log/mysql/mysql-bin.000004' at 246679, the last byte read from '/var/log/mysql/mysql-bin.000004' at 246679

[shlomi-noach]

What's your select version()? I'm curious since I never got this error.

[cypissa]

mysql> SELECT VERSION();
+------------+
| VERSION()  |
+------------+
| 5.6.34-log |
+------------+
1 row in set (0.00 sec)

I've noticed the same error with mysql 5.6.19.
I tested a little since yesterday and so far migrations were able to successfully done despite the error.

Some time ago I've tested under heavy traffic and I remember there were some problems with migration, unfortunately I'm not 100% they were connected to this specific error, because I had also another problems I solved on the way. Now I can't reproduce failed migration (even though the error is present), but I don't have possibility to test under heavy traffic for now.

As an additional information, when I see the error I also see a lot of messages like:

DEBUG Skipping handled query at mysql-bin.000004:35549

Setting unique serverId solves this.

[shlomi-noach]

Thank you