| From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, <robertmhaas(at)gmail(dot)com>, <craig(at)2ndquadrant(dot)com>, <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Protect syscache from bloating with negative cache entries |
| Date: | 2017-01-23 14:16:49 |
| Message-ID: | 6519b7ad-0aa6-c9f4-8869-20691107fb69@BlueTreble.com |
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| Lists: | pgsql-hackers |
On 1/22/17 5:03 PM, Tom Lane wrote:
>> Ok, after reading the code I see I only partly understood what you were
>> saying. In any case, it might still be useful to do some testing with
>> CATCACHE_STATS defined to see if there's caches that don't accumulate a
>> lot of negative entries.
> There definitely are, according to my testing, but by the same token
> it's not clear that a shutoff check would save anything.
Currently they wouldn't, but there's concerns about the performance of
some of the other ideas in this thread. Getting rid of negative entries
that don't really help could reduce some of those concerns. Or perhaps
the original complaint about STATRELATTINH could be solved by just
disabling negative entries on that cache.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
855-TREBLE2 (855-873-2532)
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