Alternate Buffer (-B2) question.

Posted by Admin on 10-May-2012 14:34

I recently started using the Alternate Buffer option for several HOT tables and indexes.

I have a question about the LRU2 replacement policy. The default

policy is DISABLED. Does it become enabled automaticlly when

the buffer space is exausted?

Also, once the space is exausted, will Progress allow more

data to be added?


David Valpreda

All Replies

Posted by gus on 10-May-2012 15:59

Yes, lru replacement will be automatically enabled.

Once all the buffers have been used, no more data can be /added/. Instead, new blocks will replace old ones. When a block not in the alternate buffer pool is requested, a block already in the pool will have to be discarded. If the block chosen to be discarded has been modified, it must first be written to disk and then discarded, after which the new block can be read.

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