Re: "Missing" column in Postgres logical replication update message

Adrian Klaver <adrian.klaver@aklaver.com> writes:
> On 8/3/22 08:09, Kevin Martin wrote:
>> I thought that any UPDATE message in the replication logs is designed to
>> include all values for all columns.  Is that correct?

Buried deep in the wire protocol specification is this bit:

----
The following message parts are shared by the above messages.

    TupleData

    Int16
        Number of columns.

    Next, one of the following submessages appears for each column (except generated columns):

    ...

    Byte1('u')
        Identifies unchanged TOASTed value (the actual value is not sent).
----

So that right there is two cases where we omit data for a column.
I suspect the "unchanged toasted data" case is what matters for
your purposes.  Maybe you've found some code that fails to implement
that correctly?

            regards, tom lane