Data Layout on Disk
Understand the layout of fixed length and variable length records on a disk.
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Database systems store the data on filesystems in the disk. The system further breaks down files into fixed-size units called pages. A page is a basic structure to organize data and index files on disk and the data transfer unit. Each page in the filesystem can hold from 4kb to 16kb.
Fixed-size page
The layout with fixed-size pages includes a group of pages, each with a constant size. A page or group of pages includes records of primitive and complex types. Every page contains data and a pointer to the next page. Each record on a fixed-size page should fit into a page. If the record size exceeds the page size, the layout uses pointers to connect multiple pages to store a single record.
The major problem with fixed-size pages is variable-size records. If the record size is less than the size of the page, the layout can only partially fit the data record. Unfortunately, this process leads to ...