Re: Per-function GUC settings: trickier than it looked

Tom Lane wrote:
> "Florian G. Pflug" <fgp@phlo.org> writes:
>> At least for me, the least surprising behaviour would be to
>> revert it too. Than the rule becomes "a function is always
>> executed in a pseudo-subtransaction that affects only GUCs"
> 
> Only if it has at least one SET clause.  The overhead is too high
> to insist on this for every function call.

In that case, I agree that only variables specified in a SET-clause
should be reverted. Otherwise, adding or removing
SET-clauses (e.g, because you chose a different implementation
of a function that suddenly doesn't need regexps anymore) will
cause quite arbitrary behavior changes.

And the rule becomes (I tend to forget things, so I like simple
rules that I can remember ;-) ) "For each SET-clause, there is
a pseudo-subtransaction affecting only *this* GUC".

greetings, Florian Pflug