On 2017-06-08 03:14:55 +0200, Petr Jelinek wrote: > On 08/06/17 03:08, Craig Ringer wrote: > > On 7 June 2017 at 18:16, sanyam jain <sanyamjai...@live.in> wrote: > >> Hi, > >> > >> Can someone explain the usage of exporting snapshot when a logical > >> replication slot is created? > > > > It's used to pg_dump the schema at a consistent point in history where > > all xacts are known to be in the snapshot (and thus dumped) or known > > not to be (so they'll be streamed out on the slot). > > > > Not just schema, it can also be used to get existing data at consistent > point in history so that changes will follow without gaps or duplicates. > > That being said, the built-in logical replication isn't using the > exported snapshots at all.
Just because it uses them in the same session doesn't really change the picture, that's more or less just an optimization. It's essentially just a cheaper version of importing a snapshot that'd have to be exported in same session. - Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
