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In software engineering, in-memory processing is a software architecture where a database is kept entirely in random-access memory (RAM) or flash memory so that usual accesses, in particular read or query operations, do not require access to disk storage. [2]
In-memory databases are faster than disk-optimized databases because disk access is slower than memory access and the internal optimization algorithms are simpler and execute fewer CPU instructions. Accessing data in memory eliminates seek time when querying the data, which provides faster and more predictable performance than disk. [1] [2]
Blocking is almost universally employed when storing data to 9-track magnetic tape, NAND flash memory, and rotating media such as floppy disks, hard disks, and optical discs. Most file systems are based on a block device , which is a level of abstraction for the hardware responsible for storing and retrieving specified blocks of data, though ...
Although sharing a similar name, heap files are widely different from in-memory heaps. In-memory heaps are ordered, as opposed to heap files. Simplest and most basic method insert efficient, with new records added at the end of the file, providing chronological order; retrieval efficient when the handle to the memory is the address of the memory
Pages in the page cache modified after being brought in are called dirty pages. [5] Since non-dirty pages in the page cache have identical copies in secondary storage (e.g. hard disk drive or solid-state drive), discarding and reusing their space is much quicker than paging out application memory, and is often preferred over flushing the dirty pages into secondary storage and reusing their space.
Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system. [1] [2] [3] A transfer of pages between main memory and an auxiliary store, such as a hard disk drive, is referred to as paging or swapping. [4]
The required disk space may be easily allocated on systems with more recent specifications (i.e. a system with 3 GB of memory having a 6 GB fixed-size page file on a 750 GB disk drive, or a system with 6 GB of memory and a 16 GB fixed-size page file and 2 TB of disk space).
Holographic storage would be non-volatile, sequential-access, and either write-once or read/write storage. It might be used for secondary and off-line storage. See Holographic Versatile Disc (HVD). Molecular memory stores information in polymer that can store electric charge. Molecular memory might be especially suited for primary storage.