Bug to apply migration if binlog is compressed.

[ciceroverneck]

Database Version: 10.2.25-MariaDB
OS: debian-linux-gnu

The bug happens if the bank is set to save compressed binlog. '

MariaDB [(none)]> show variables like 'log_bin_compress';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| log_bin_compress | ON    |
+------------------+-------+

Behavior:
The whole process happens correctly, but after the postponing file removal the following log occurs:

2019-11-13 17:53:21 INFO Grabbing voluntary lock: gh-ost.1276299.lock
2019-11-13 17:53:21 INFO Setting LOCK timeout as 6 seconds
2019-11-13 17:53:21 INFO Looking for magic cut-over table
2019-11-13 17:53:21 INFO Creating magic cut-over table `cifra`.`_songbook_log_del`
2019-11-13 17:53:21 INFO Magic cut-over table created
2019-11-13 17:53:21 INFO Locking `cifra`.`songbook_log`, `cifra`.`_songbook_log_del`
2019-11-13 17:53:22 INFO Tables locked
2019-11-13 17:53:22 INFO Session locking original & magic tables is 1276299
2019-11-13 17:53:22 INFO Writing changelog state: AllEventsUpToLockProcessed:1573667602084929375
2019-11-13 17:53:22 INFO Waiting for events up to lock
2019-11-13 17:53:25 ERROR Timeout while waiting for events up to lock
2019-11-13 17:53:25 ERROR 2019-11-13 17:53:25 ERROR Timeout while waiting for events up to lock
2019-11-13 17:53:25 INFO Looking for magic cut-over table
2019-11-13 17:53:25 INFO Will now proceed to drop magic table and unlock tables
2019-11-13 17:53:25 INFO Dropping magic cut-over table
2019-11-13 17:53:25 INFO Releasing lock from `cifra`.`songbook_log`, `cifra`.`_songbook_log_del`
2019-11-13 17:53:25 INFO Tables unlocked

[timvaillancourt]

👋 @ciceroverneck gh-ost does not support MariaDB's binlog compression feature. My guess is the go mysql driver, the go-mysql library (dependency), etc does not understand this feature

I'll create a PR to add this as a limitation and we welcome PRs to add support for this as a new feature