On 04/10/18 00:30, Andrew Gierth wrote: > That's not precisely true - ultimately, the routines that do actual > scans take the snapshot to use as a parameter, and the executor mostly > references the snapshot from the EState; but a bunch of places do > require that ActiveSnapshot be set to the currently applicable snapshot > (e.g. for queries inside stable functions nested inside the main query).
I'm becoming increasingly glad I asked (or less embarrassed that I hadn't figured it all out yet). :) Am I right in thinking that, for my original purpose of detoasting something later in a transaction, all that matters is that I registered a snapshot from the time at which I copied the toasted datum, and the resource owner I registered it to has not been released yet, so rows referred to in the snapshot haven't been vacuumed away? Is that a sufficient condition for detoast to work? Or would I need to do something more, like push and pop that snapshot around the detoast call? This would be in a PL function (or the handler for the PL function), if the context matters. -Chap
