Re: 2nd Level Buffer Cache

Excerpts from rsmogura's message of vie mar 18 11:57:48 -0300 2011:

>  Actually idea of this patch was like this:
>  Some operations requires many buffers, PG uses "clock sweep" to get 
>  next free buffer, so it may overwrite index buffer. From point of view 
>  of good database design We should use indices, so purging out index from 
>  cache will affect performance.

The BufferAccessStrategy stuff was written to solve this problem.

>  As the side effect I saw that this 2nd level keeps pg_* indices in 
>  memory too, so I think to include 3rd level cache for some pg_* tables.

Keep in mind that there's already another layer of caching (see
syscache.c) for system catalogs on top of the buffer cache.

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Álvaro Herrera <alvherre@commandprompt.com>
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