On 22 March 2017 at 01:17, Robert Haas <robertmh...@gmail.com> wrote:
> On Sun, Mar 12, 2017 at 10:20 PM, Thomas Munro > <thomas.mu...@enterprisedb.com> wrote: > > Maybe someone can think of a clever way for an extension to insert a > > wait for a user-supplied LSN *before* acquiring a snapshot so it can > > work for the higher levels, or maybe the hooks should go into core > > PostgreSQL so that the extension can exist as an external project not > > requiring a patched PostgreSQL installation, or maybe this should be > > done with new core syntax that extends transaction commands. Do other > > people have views on this? > > IMHO, trying to do this using a function-based interface is a really > bad idea for exactly the reasons you mention. I don't see why we'd > resist the idea of core syntax here; transactions are a core part of > PostgreSQL. > > There is, of course, the question of whether making LSNs such a > user-visible thing is a good idea in the first place, but that's a > separate question from issue of what syntax for such a thing is best. (I know this is old, but): That ship sailed a long time ago unfortunately, they're all over pg_stat_replication and pg_replication_slots and so on. They're already routinely used for monitoring replication lag in bytes, waiting for a peer to catch up, etc. -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
