Re: Allow logical replication to copy tables in binary format

On Mon, Jan 30, 2023 at 4:19 PM Melih Mutlu <m.melihmutlu@gmail.com> wrote:
>> 8. Note that the COPY binary format isn't portable across platforms
>> (Windows to Linux for instance) or major versions
>> https://www.postgresql.org/docs/devel/sql-copy.html, whereas, logical
>> replication is https://www.postgresql.org/docs/devel/logical-replication.html.
>> I don't see any handling of such cases in copy_table but only a check
>> for the publisher version. I think we need to account for all the
>> cases - allow binary COPY only when publisher and subscriber are of
>> same versions, architectures, platforms. The trick here is how we
>> identify if the subscriber is of the same type and taste
>> (architectures and platforms) as the publisher. Looking for
>> PG_VERSION_STR of publisher and subscriber might be naive, but I'm not
>> sure if there's a better way to do it.
>
>
> I think having the "copy_format" option with text as default, like I replied to your 3rd review above, will keep things as they are now.
> The patch now will only allow users to choose binary copy as well, if they want it and acknowledge the limitations that come with binary copy.
> COPY command's portability issues shouldn't be an issue right now, since the patch still supports text format. Right?
>

One thing that is not completely clear from above is whether we will
have any problem if the subscription uses binary mode for copying
across the server versions. Do we use binary file during the copy used
in logical replication?

So, doesn't this mean that there is no separate failure mode during
the initial copy? I am clarifying this to see if the patch really
needs a separate copy_format option for initial sync?