Buffers and LRU.

Hello. I'm beginner in use Informix. Where can I find what are the main difference between buffers and LRU queue. Thanks for your help T.K

The buffer pool is the page cache of the engine. The LRUs are simply a means of chaining the buffers together. There are two chains per LRU - the free and the dirty. (Actually a free buffer has a page in it, but it is not dirty.) There are multiple LRUs so that if a thread tries to access one of the chains to find a free buffer and that chain is currently locked, then it will try one of the other chains. So it is basically a means of creating a hash array of the buffer pool so that the page access is partitioned. LRU stands for Last Recently Used. As a page is referenced, it is removed from it's chain and placed at the head of the last recently used chain. When a free buffer is needed, the tail buffer of an LRU is used. Therefor, we tend to reuse a page buffer that is not being used a lot rather than a page buffer that is highly referenced. This is a fairly common technique used by most queue management systems for caching. "T.K" <gp@tf.de> wrote in message news:bvrslu$67h$1@inews.gazeta.pl... > Hello. > I'm beginner in use Informix. > Where can I find what are the main difference between > buffers and LRU queue. > > Thanks for your help > > T.K > >