DB File Management

DB File Structures

• Unordered Heap Files
  • Records placed arbitrarily across pages
  • Linked list or Page directory
• Clustered Heap Files
  • Records and pages are grouped
• Sorted Files
  • Pages and records are in sorted order
• Index Files
  • B+ Trees, Linear Hashing, …
  • May contain records or point to records in other files

Records

• Fixed Length Records (FLR)
  • Unpacked: Use Bitmap
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• Variable Length Records (VLR)
  • Slotted Page
    • each page uses a page footer that maintains a slot directory tracking slot count, a free space pointer, and entries.
    • The slot count tracks the total number of slots. This includes both filled and empty slots.
    • The free space pointer points to the next free position within the page.
    • Full when footer and records come together.
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