On Thu, Mar 13, 2014 at 11:42 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> On 2014-03-13 11:26:10 -0400, Robert Haas wrote:
>> On Thu, Mar 13, 2014 at 11:11 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> > If there's not a catcache for pg_seclabels, I'd have no objection
>> > to adding one. As for your "userland cache" objection, you certainly
>> > could build such a thing using the existing inval callbacks (if we
>> > had a catcache on pg_seclabels), and in any case what have userland
>> > caches got to do with relcache?
>>
>> I avoided doing that for the same reasons that we've been careful to
>> add no such cache to pg_largeobject_metadata: the number of large
>> objects could be big enough to cause problems with backend memory
>> consumption. Note that large objects are one of the object types to
>> which security labels can be applied, so any concern that applies
>> there also applies here.
>
> Good point.
>
> Are you primarily worried about the size of the cache, or about the size
> of the queued invaldations?
Mostly the former. I can't really see the latter being a big deal. I
mean, if you do a lot of DDL, you'll get more sinval resets, but oh
well. We can't optimize away re-examining the data when it actually is
changing underneath us.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
