Failover slots are optional. And they work on master.
While the other approach could also work, it will work later and still require a slot on the master.
=> I don't see why having Failover Slots in 9.6 would prevent us from having something else later, if someone else writes it.
We don't need to add this to core. Each plugin can independently write is own failover code. Works, but doesn't seem like the right approach for open source.
=> I think we should add Failover Slots to 9.6.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services