| From: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
|---|---|
| To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
| Cc: | Craig Ringer <craig(at)2ndquadrant(dot)com>, Fabrízio de Royes Mello <fabriziomello(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Joe Conway <mail(at)joeconway(dot)com> |
| Subject: | Re: proposal: session server side variables |
| Date: | 2017-01-04 17:49:56 |
| Message-ID: | alpine.DEB.2.20.1701041843000.22281@lancre |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
> 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 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.
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.
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