Re: Allow logical replication to copy tables in binary format

On Sat, Mar 18, 2023 at 3:11 PM Peter Smith <smithpb2250@gmail.com> wrote:
>
> On Fri, Mar 17, 2023 at 11:25 PM Melih Mutlu <m.melihmutlu@gmail.com> wrote:
> ======
> src/backend/replication/logical/tablesync.c
>
> 2.
> @@ -1168,6 +1170,15 @@ copy_table(Relation rel)
>
>   appendStringInfoString(&cmd, ") TO STDOUT");
>   }
> +
> + /* The binary option for replication is supported since v16 */
> + if (walrcv_server_version(LogRepWorkerWalRcvConn) >= 160000 &&
> + MySubscription->binary)
> + {
> + appendStringInfoString(&cmd, " WITH (FORMAT binary)");
> + options = lappend(options, makeDefElem("format", (Node *)
> makeString("binary"), -1));
> + }
>
>
> Logical replication binary mode was introduced in v14, so the old
> comment ("The binary option for replication is supported since v14")
> was correct. Unfortunately, after changing the code check to 16000, I
> think the new comment ("The binary option for replication is supported
> since v16") became incorrect, and so it needs some rewording. Maybe it
> should say something like below:
>
> SUGGESTION
> If the publisher is v16 or later, then any initial table
> synchronization will use the same format as specified by the
> subscription binary mode. If the publisher is before v16, then any
> initial table synchronization will use text format regardless of the
> subscription binary mode.
>

I agree that the previous comment should be updated but I would prefer
something along the lines: "Prior to v16, initial table
synchronization will use text format even if the binary option is
enabled for a subscription."

--
With Regards,
Amit Kapila.