DIRTY PAGE Meaning and
Definition
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A dirty page, in the context of computer science and database systems, refers to a data page that has been modified or updated in primary memory (RAM) and needs to be written back to the secondary storage (disk) for permanent storage.
In a traditional disk-based database system, data is stored in pages on the disk, and when a modification or update is made to a page in memory, it becomes "dirty" as the content in both memory and disk is no longer the same. The dirty page needs to be subsequently synchronized with the disk version to ensure data persistence and consistency.
Dirty pages are typically managed by a buffer pool or cache in memory, which holds frequently accessed data pages to improve database performance. When a dirty page is evicted from the buffer pool, it must be written back to disk to preserve data durability.
To facilitate efficient management of dirty pages and minimize disk I/O operations, database systems often employ strategies like write-back or write-through caching. In write-back caching, dirty pages are written back to disk in batches or when necessary, while in write-through caching, modifications are immediately propagated to the disk. The frequency and timing of writing dirty pages back to disk can be influenced by factors like system load, transaction volume, and recovery requirements.
Ensuring that dirty pages are consistently and timely written back to disk is essential for maintaining the integrity and reliability of data in a disk-based database system.
Common Misspellings for DIRTY PAGE
- dity page
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- xirty page
- firty page
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Etymology of DIRTY PAGE
The term "dirty page" in the field of computer science refers to a type of page or memory block that has been modified but not yet saved to the disk. The term derives from the analogy of a "dirty" physical page or sheet of paper that has been written on but has not been cleaned or erased.
In computer systems that use virtual memory, the data is stored in a hierarchy of memory levels, with the main memory (RAM) acting as a cache for the data that resides on the slower disk storage. When a modified page in the RAM needs to be replaced with another page, it becomes a "dirty page" because its content has been altered since it was loaded from disk. Before it can be flushed out of the memory, it must be saved or "cleaned" to the disk to ensure durability of the modifications.
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