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Re: How to get SE-PostgreSQL acceptable

From: KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Joshua Brindle <method(at)manicmethod(dot)com>, Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, KaiGai Kohei <kaigai(at)kaigai(dot)gr(dot)jp>, Peter Eisentraut <peter_e(at)gmx(dot)net>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: How to get SE-PostgreSQL acceptable
Date: 2009-01-29 04:10:58
Message-ID: 49812C52.8090400@ak.jp.nec.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Robert Haas wrote:
> On Wed, Jan 28, 2009 at 10:15 PM, KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com> wrote:
>> It seems to me reference-counter is more preferable than boolean,
>> at least. But it makes performance pain on writer access when it
>> is expanded to row-level security.
> 
> A reference counter will never work. You could easily end up
> serializing all access to the database around the row-level lock on
> one popular security context.  That is a performance problem two or
> three orders of magnitude worse than anything that has been suggested
> so far in connection with this feature, and probably six orders of
> magnitude worse than the problem you're trying to solve (pg_security,
> or whatever we want to call it, getting too big).

Yes, I don't think it is a good approach also.
Just I though it was relatively preferable than boolean.

> For the record, I think Tom's concern in this area is largely
> off-base, especially in light of the fact that Joshua Brindle and
> Kaigai both agree that churn is not likely to be large.  I think we
> need some kind of plausible way to clean out the table, but I don't
> think it needs to be fully automated or super-efficient, just
> something that someone could do if they felt the need.

If pg_security is actually overflowed or makes compress storages
by unused ones, I recommend to stop the system and run a utility
to reclaim them. But I don't think it actually happen.

Thanks,
-- 
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>

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