Re: Why is autovacuum_freeze_max_age a postmaster setting?

Hi,

On 2014-03-21 16:49:53 -0500, Jim Nasby wrote:
> Why do we require a restart to change autovacuum_freeze_max_age? Can’t
> we respawn the autovac workers to pick up the setting? (Or just pass
> the HUP down to them?)

It's more complex than notifying the workers. There's limits in shared
memory that's computed based on it. Check
varsup.c:SetTransactionIdLimit(). It's not entirely trivial to trigger
recomputation of that value via the GUC machinery in a sensible way...

But yes, I'd wished it were PGC_SIGHUP before as well.

I guess we could delegate responsibility of updating the shared memory
value to the autovac launcher?

Greetings,

Andres Freund

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