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Re: Whether the function exists a in pgsql table or not?

From: Greg Smith <greg(at)2ndQuadrant(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Whether the function exists a in pgsql table or not?
Date: 2011-08-29 03:00:35
Message-ID: 4E5B00D3.9090904@2ndQuadrant.com (view raw or flat)
Thread:
Lists: pgsql-general
On 08/27/2011 01:21 PM, shuaixf wrote:
> In Oracle, when the table has few records, used frequently, it would use
> "storage(buffer_pool keep)" to keep the data in cache instead of LRU
> algorithm.
>
> if the function exists in a pgsql table or not?
>    

There aren't any controls to pin a table into memory in PostgreSQL.  The 
way the database uses both its dedicated buffer cache as well as the OS 
one, it's hard to even define such a UI that would make sense--the 
database doesn't have any control or interaction with the OS cache.

The mechanism for deciding what stays in the PostgreSQL cache is a bit 
more complicated than an LRU, while the one in the OS probably is a 
LRU.  If the table is used frequently, it's very likely to stay in one 
of the two caches anyway.

-- 
Greg Smith   2ndQuadrant US    greg(at)2ndQuadrant(dot)com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.


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