Re: proposal: session server side variables

2017-01-04 18:49 GMT+01:00 Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>:

>
> ok understand
>>
>
> Good. So we seem to agree that GUCS are transactional?
>
> The logic depends on transactions and on nesting level (nesting doesn't
>> depends on transactions only)
>>
>
> Yep, it probably also happens with LOCAL which hides the previous value
> and restores the initial one when exiting.
>
> void AtEOXact_GUC(bool isCommit, int nestLevel)
>>
>> Probably we should to use CallXactCallbacks instead - then is not a
>> performance impact when there are not transactional variables.
>>
>
> I do not understand your point.
>

It is on critical path, so every check increase computer time for
transaction end.

Regards

Pavel

>
> It is a very good thing that GUCs are transactional, and this should not
> be changed, it is a useful feature! Much more useful than non transactional.
>

Personally, I never used - although I using often nesting

regards

Pavel

>
> Moreover I think that transactional is expensive when writing things to
> disk, but in memory the overhead is reduced, and if you need it then you
> need it.
>
> --
> Fabien.
>