Cache buffers chains&n…

最新推荐文章于 2025-08-06 12:51:52 发布

最新推荐文章于 2025-08-06 12:51:52 发布 · 87 阅读

本文深入探讨了数据库缓存中的两种关键锁机制：Cachebufferchainslatch和LRUchainlatch。解释了它们在数据块访问过程中的作用，以及如何通过优化SQL调用和I/O请求来减少逻辑I/O rates，避免热点块现象。同时阐述了这两个锁在数据块写入和LRU链操作时的必要性。

Cache buffers chains latch

This latch is acquired whenever a block in the buffer cache is accessed (pinned).Reducing contention for the cache buffer chains latch will usually require reducing logical I/O rates by tuning and minimizing the I/O requirements of the SQL involved. High I/O rates could be a sign of a hot block (meaning a block highly accessed).

当一个数据块被存取时，这个锁会自动获取。为了减少cache buffer chains latch的争用，一般会通过调优，和最小化sql调用产生的I/O请求来减少逻辑I/O rates<wbr>；高</wbr>I/O rates 标志着热点块（意味着这个块非常高的存取）

Cache buffers LRU chain latch

The cache buffer lru chain latch is acquired in order to introduce a new block into the buffer cache and when writing a buffer back to disk, specifically when trying to scan the LRU (least recently used) chain containing all the dirty blocks in the buffer cache.
为了说明一个新的数据块要写到buffer cache中，及当把一个buffer cache 写回到disk，特别是在扫描LRU chain 中包含的所有buffer cache 中的脏数据块（dity block），时才去获得cache buffer lru chain latch 。