pt-table-checksum --ignore-columns should support table name

[Lachlan Pease]

As of percona-toolkit 3.0.2, the ignore-columns option to pt-table-checksum is only useful in a single table context.

Because this column filter is applied to all tables, it's often necessary to break a checksum run into multiple executions in order to make sure that similarly named columns in other tables aren't affected.

I would like to propose extending the ignore-columns option to accept strings of the format 'tablename.columnname', mirroring the ignore-tables option and it's 'schemaname.tablename' format.

My particular usecase involves virtual columns which are missing on the slave (due to it's use of TokuDB), which might also be solved by extending pt-table-checksum to ignore virtual columns. However, I believe that extending --ignore-columns is the more robust option.

Not sure if you guys accept patches, but I'm happy to provide one if need be.

[Carlos Salguero (carlos-salguero)]

Hi,

Thanks for contributing with interesting ideas like this one.
I definitely believe this is a good feature I would like to include.
If you already have a patch or want to start with it, you can read the contributing guide at https://github.com/percona/percona-toolkit/blob/3.0/CONTRIBUTE.md.
There you will find general guidelines and some help about how to set up the dev environment, start a sandbox, etc.
Feel free to contact me if you need some assistance.

Thanks again.

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PT-731