Re: shared_preload_libraries is ignored in single user mode

2010/8/16 KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>:
>> I don't really see what the advantage of doing this in single-user
>> mode is.  If the overhead of permissions-checking is enough to matter,
>> maybe that's a sign we're doing something wrong.
>>
> Hmm... I guess the overhead is not a significant matter, because the
> number of system obejcts (not only tables) are less than 3,500.
> It will be small enough on recent hardware.

I would think so. More to the point, what is the cost of checking
permissions as a percentage of the cost of applying the new labels?
If it isn't pretty small, something's not right. Performance will
probably be terrible if anyone actually attempts to use this do to
real work.

> I might have a reason why the script need to launch in single-user
> mode, but it is not clear right now, sorry.

Another point here is that I wonder if we really need to label system
objects at all. Are you applying the same label to all of them? If
so, perhaps it might be feasible to set up the code so that it simply
assumes that label for every object in the pg_catalog namespace.

And if you're NOT setting the label the same way on all of them, then
there's a maintenance issue to think about.

--
Robert Haas
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