Re: jit and explain nontext

Hi,

On 2020-10-15 14:51:38 +1300, David Rowley wrote:
> That's a pretty good point. If we do SET enable_sort TO off; then
> cached plans are unaffected.

In contrast to that we do however use the current work_mem for
execution, I believe. Which could be fairly nasty, if a plan was made
for a huge work_mem, for example.

> That's not the case when someone does SET jit TO off; as we'll check
> that in provider_init() during execution. Although, switching jit
> back on again works differently. If the planner saw it was off then
> switching it on again won't have existing plans use it. That's
> slightly weird, but perhaps it was done that way to ensure there was a
> hard off switch.

It was motivated by not wanting to just enable JIT for queries that were
prepared within something like SET LOCAL jit=off;PREPARE; RESET
jit;. I'm open to revising it, but that's where it's coming from.

Greetings,

Andres Freund