sizeextent

Sizeextent is a term used in storage and database systems to denote the size of an extent, a basic allocation unit representing a contiguous range of storage. An extent is allocated to hold part or all of a file, a database segment, or other data structure; the size extent is the length of that contiguous region, typically expressed in blocks or bytes. The concept appears in several domains, and the exact meaning or usage can vary by platform.

In file systems, extents map file data to a sequence of physical blocks. The size extent can be fixed at format time or configured at runtime, and it affects fragmentation, allocation overhead, and read-ahead efficiency. Larger extents reduce metadata operations but can lead to space waste when files are highly fragmented; smaller extents offer finer granularity at the cost of more metadata.

In database management systems, extents allocate disk space for tables and indexes. The size extent influences I/O patterns, cache behavior, and write amplification, and some systems allow preallocation of extents or dynamic growth.

In memory or storage allocators, extents can be used as a unit of allocation within a pool. The term sizeextent may appear in configuration or API documentation to designate the maximum or initial extent size.

Overall, sizeextent is not a universal standard term but a descriptive label for the length of a contiguous allocation unit. See also extent, allocation unit, and fragmentation.