schonlinner_at_yahoo.com wrote:
> I read that the blocks of a full table scan will be placed at the LRU
> end of the buffer cache list. But does this kind of algorithm help in
> any way in our case when the buffer cache is smaller than a table which
> is full-table-scanned?
>
> In this case I assume that a single full table scan of the large table
> will throw out everything from the buffer cache, filling it solely with
> some contents of the large table. Is this correct or am I wrong?
You are wrong. Think about the LRU algorithm: if it needs a block and there
are no empty blocks it reuses the oldest one. But since FTS puts blocks at
this end of list with oldest blocks, it will reuse the blocks it used a
moment earlier. FTS will just consume some blocks over and over again.
--
Michal Kuratczyk
Received on Mon Jun 26 2006 - 07:32:07 CDT
