Re: [HACKERS] Function to move the position of a replication slot

On 17 August 2017 at 07:30, Michael Paquier <michael.paquier@gmail.com> wrote:

Definitely agreed on that. Any move function would need to check if
the WAL position given by caller is already newer than what's
available in the local pg_wal (minimum of all other slots), with a
shared lock that would need to be taken by xlog.c when recycling past
segments. A forward function works on a single entry, which should be
disabled at the moment of the update. It looks dangerous to me to do
such an operation if there is a consumer of a slot currently on it.

pg_advance_replication_slot(...)

ERROR's on logical slot, for now. Physical slots only.

Forward-only.

Future work to allow it to use the logical decoding infrastructure to fast-forward a slot by reading only catalog change information and invalidations, either via a dummy output plugin that filters out all xacts, or by lower level use of the decoding code.

Reasonable?