The discussions I've seen indicated that, in use, tablespaces were at the database level, but, yes, the docs do say
thata table can be assigned to a defined tablespace. What I still can't find is syntax which establishes
buffers/caches/whateverand assigns them to tablespaces. Without that, I'm not sure what benefit there is to
tablespaces,other than a sort of RAID-lite.
Robert
---- Original message ----
>Date: Tue, 12 Oct 2010 08:34:23 -0400
>From: pgsql-performance-owner@postgresql.org (on behalf of Robert Haas <robertmhaas@gmail.com>)
>Subject: Re: [PERFORM] How does PG know if data is in memory?
>To: gnuoytr@rcn.com
>Cc: pgsql-performance@postgresql.org
>
>On Mon, Oct 11, 2010 at 11:11 PM, <gnuoytr@rcn.com> wrote:
>> An approach that works can be found in DB2, and likely elsewhere.
>>
>> The key is that tablespaces/tables/indexes/buffers are all attached through the bufferpool (the DB2 term). A
tablespace/bufferpoolmatch is defined. Then tables and indexes are assigned to the tablespace (and implicitly, the
bufferpool). As a result, one can effectively pin data in memory. This is very useful, but not low hanging fruit to
implement.
>>
>> The introduction of rudimentary tablespaces is a first step. I assumed that the point was to get to a DB2-like
structureat some point. Yes?
>
>We already have tablespaces, and our data already is accessed through
>the buffer pool.
>
>--
>Robert Haas
>EnterpriseDB: http://www.enterprisedb.com
>The Enterprise PostgreSQL Company
>
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