Re: Does RelCache/SysCache shrink except when relations are deleted?
От | MauMau |
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Тема | Re: Does RelCache/SysCache shrink except when relations are deleted? |
Дата | |
Msg-id | 849BF81321BF4FAAAE0FAB25E2886BFC@maumau обсуждение исходный текст |
Ответ на | Re: Does RelCache/SysCache shrink except when relations are deleted? (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
From: "Tom Lane" <tgl@sss.pgh.pa.us> > That's correct. We used to have a limit on the size of catcache > (if memory serves, it was something like 5000 entries). We got rid of > it after observing that performance fell off a cliff as soon as you had > a working set larger than the cache limit. Trust me, if we had a limit, > you'd still be here complaining, the complaint would just take a > different form ;-) Yes, I can imagine. Now I'll believe that caching catalog entries in local memory without bound is one of PostgreSQL's elaborations for performance. 64-bit computing makes that approach legit. Oracle avoids duplicate catalog entries by storing them in a shared memory, but that should necessate some kind of locking when accessing the shared catalog entries. PostgreSQL's approach, which does not require locking, is better for many-core environments. > I concur with Merlin's advice to rethink your schema. 100000 tables is > far beyond what any sane design could require, and is costing you on > many levels (I'm sure the OS and filesystem aren't that happy with it > either). I agree. I'll suggest that to the customer, too. Thank you very much. Regards MauMau
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