2015-09-26 18:17 GMT+02:00 Nikolai Zhubr <n-a-zh...@yandex.ru>: > Hi all, > > I'm trying to find a soultion to automatically execute something > (preferrably a function or at least some pure sql statements) at the > beginning and at the end of a user session. As an example, imagine just > storing of all login and logout timestamps (though the real task is a bit > more complicated than that) > > I would not like it to be somehow explicitely client-side initiated (like > e.g. trivially calling some certain do_at_sess_begin(), do_at_sess_end()) > because first, a malicious client could then mess it up easily, and > furthermore, in the case that the session somehow ended abnormally (due to > say temporary network fault) client-side finalizer function would not be > called anyway. > > My first try was to create an event trigger for sql drop events, then > create a temporary table and watch for its drop at the end of a session. > However, it seems drop events are just not fired for temporary tables > (although documentation does not state this anywhere, as far as I can see, > maybe I'm wrong about that) > > It would seem like one of the simplest things ever, but I'm now totally > stuck out of ideas. > > As a partial solution, handling just session _end_ would already be OK.
> Any thoughts? > This cannot be solved without patching PostgreSQL source code :( . There are not good hooks for custom extension. Patch is relative simple, but I cannot to publish it. You have to modify main loop in src/backend/tcop/postgres.c file. Login point can be immediately before loop. Logout point can be joined to 'X',EOF message. Attention - there are some corner case, what are necessary to solve - mainly how to handle exceptions in login/logout procedures. Regards Pavel p.s. I understand so this hack is necessary for porting older application from other databases, but I am not sure if it is a good idea to use it. Not all tasks can be solved well in database. > > > Thank you, > Nikolai > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general >
