FIFO/LRU queues

A buffer holds data for the purpose of caching. The database server uses the least-recently used (LRU) queues to replace the cached data. HCL Informix® also has a first-in first-out (FIFO) queue. When you set the number of LRU queues, you are actually setting the number of FIFO/LRU queues.

Use the BUFFERPOOL configuration parameter to specify information about the buffer pool, including information about the number of LRU queues to create when database server shared memory is set up and values for lru_min_dirty and lru_max_dirty, which control how frequently the shared-memory buffers are flushed to disk.

To improve transaction throughput, increase the lru_min_dirty and lru_max_dirty values. However, do not change the gap between the lru_min_dirty and lru_max_dirty values. If the AUTO_LRU_TUNING configuration parameter is enabled, the values of the lru_max_dirty and lru_min_dirty fields are reset automatically as needed to improve performance.


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