PPT Slide
Logical File Structure
- Files are referenced by the operating system in three possible atomic forms (Figure 16.4):
- Bytes (“flat file”) - typical of UNIX
- Fixed-length records - think: tapes
- Variable-length records - think: database records
- In general, older OSes tended to support multiple file formats. Trend is towards treating files as mere byte streams, letting the application layers decided how to impose structure. High-end database servers can even manage the drive directly, bypassing the file system altogether (Figure 16.5).
- Files vary from 0 bytes to very large (usually limited by “native math” of machine’s registers).
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