RE: Patch for migration of the pg_commit_ts directory

Dear Sergey,

> I was writing emails in the browser. I am writing this letter and
> sending it in the mail client. The letter format is plain text. I think
> this should fix the problem.

Yes, solved. Thanks for the corporation.

> You do not need to check for files in the pg_commit_ts directory in the
> new cluster BEFORE the copy operation. These files are not needed. This
> patch is designed to copy the pg_commit_ts directory from the old
> cluster. If the user does not want to copy the pg_commit_ts directory,
> it is enough not to specify the --pg-commit-ts option. This is the
> default behavior. And for most, this is a suitable option.

OK, understood. Let me think over it again...

BTW, I still think this patch must be coordinate with the migration of replication
origins [1], and this patch itself should not handle the origin migration.
To separate them clearly, I split your patch into three parts:

0001 - migrate commit_ts sub directory.
0002 - add --pg-commit-ts option. (Actually I'm not sure it's needed)
0003 - Save and restore the roident and remote_lsn from the old cluster.
IIUC it's not needed if [1] is pushed.

I feel this method allows patches to be pushed separately. How do you feel?

[1]: https://www.postgresql.org/message-id/CAFPTHDbPXU7cs189J=BrzSa20EJzajOU25N7G7nT6UZqMkRnXg@mail.gmail.com

Best regards,
Hayato Kuroda
FUJITSU LIMITED