Re: logical copy_replication_slot issues

Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com> writes:

> /*
> - * Create logical decoding context, to build the initial snapshot.
> + * Create logical decoding context to find start point or, if we don't
> + * need it, to 1) bump slot's restart_lsn and xmin 2) check plugin sanity.
> */
>
> Do we need to numbering that despite not referring them?

No, it just seemed clearer to me this way. I don't mind removing the
numbers if you feel this is better.

> ctx = CreateInitDecodingContext(plugin, NIL,
> - false, /* do not build snapshot */
> + false, /* do not build data snapshot */
> restart_lsn,
> logical_read_local_xlog_page, NULL, NULL,
> NULL);
> I'm not sure this change makes the comment better. Could you elaborate
> on the motivation of this change?

Well, DecodingContextFindStartpoint always builds a snapshot allowing
historical *catalog* lookups. This bool controls whether the snapshot
should additionally be suitable for looking at the actual data, this is
e.g. used by initial data sync in the native logical replication.

-- cheers, arseny