README: run_mode flag appears to be obsolete

[jogaco]

From source code, this flag seems to be execute now, with values true, false.

[steverice]

@jogaco run_mode still controls whether the command will be printed or run by pt-online-schema-change, as stated in the README.
The execute flag seen in source controls whether pt-online-schema-change is passed the --dry-run or --execute flag.

It's a bit of an unfortunate naming collision — I'll look to change that in a future refactor 😁

[jogaco]

Something related to this is not working smoothly.
When I use:

  percona:
    run_mode: execute
    defaults-file: /etc/mysql/percona-user.cnf
    username: root
    execute: true
    log: ./log/pt-schema.log

I get:

Segmentation fault (core dumped)
rake aborted!
StandardError: An error has occurred, all later migrations canceled:

If I remove

    execute: true

All works well, even though pt-online-schema-change prints this message:

Starting a dry run.  `mydatabase`.`mytable` will not be altered.  Specify --execute instead of --dry-run to alter the table.

But the changes are there after finishing the rake task.
Maybe something odd with ptosc ? Using 2.2.14.

[steverice]

Could be a pt-osc issue. What are the contents of your pt-schema.log? You may also want to copy the command from there and run it with a debug flag to get more info.