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This article mainly introduces "how to understand the latch waiting of the DB BUFFER LRU list". In the daily operation, I believe many people have doubts about how to understand the latch waiting of the DB BUFFER LRU list. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubts of "how to understand the latch waiting of the DB BUFFER LRU list". Next, please follow the editor to study!

It is concluded that the following two situations can cause latch to wait:

1. Load memory and write to LRU list

When the process wants to read blocks that are not yet loaded into memory, it is allocated to the required free buffer by querying the LRU column, and cache buffers lru chain latch is required in the process.

two。 Brush dirty blocks and synchronize to physical files

The database write process records the dirty buffer to the file, queries LRU LIST, and gets the cache buffers lru chain latch when the corresponding buffer is moved to FREE LIST.

Record the dirty buffer to a file in the following cases:

2.1) when the service process corresponding to session requests to record a dirty buffer from DBWR in order to obtain a free buffer

2.2) when the Oracle process requests to record the dirty buffer of the related object in order to perform work such as Parallel Query or Backup,Truncate/Drop

2.3) when periodic or administrative cause checkpoints (checkpointing) are performed.

2.4) Oracle periodically performs checkpoints in order to ensure recovery at the time specified by FAST_START_MTTR_TARGET (or LOG_CHECKPOINT_TIMEOUT).

2.5) checkpoints also occur when the administrator executes a checkpoint command or switches according to the log file.

At this point, the study of "how to understand the latch waiting of DB BUFFER LRU list" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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