Setting issues

[ksaito7]

• SettingsManager controls transaction for SettingsCatalog. So checkpoints can’t recover settings due to nested transaction.
• ~~Can’t add new settings after Peloton booting. So we can’t implement SET command.~~
• There is no update function in SettingsCatalog.
• Why setting control functions are static?

So I propose setting refactoring for SettingManager and SettingsCatalog. Basically, I think setting user should control all functions through SettingManager, not static like other manager. Refactor points are below:

• All setting values are controlled through SettingsManager (Set/Get value, ~~Add setting~~)
• A TransactionContext is passed through the function argument.
• Implement update function in SettingsCatalog.

[tli2]

There is a bunch of Set methods in SettingsManager. I don't know how they interact with transactions though.

[ksaito7]

Set methods are just update methods for existed setting value using setting_id. These can not create new settings actually.

[pervazea]

What new settings do you wish to add (after the system has booted)?

[ksaito7]

I wanted users to be able to add original variables through SET command in psql or config files. But I found that Postgres can't set the original variables. I misunderstood that. Delete its line.