Files: Main Problem

• How to store tables into disks?

  

• Q: 512Byte block. 80Byte tuple. How to store?

Spanned vs Unspanned

In the previous example, 512 bytes can store 6 full tuples with the remaining of 32 bytes

The maximum space wasted is 50% of the block size - 1 byte

Variable-Length Tuples

• How do we store them?

  

• Reserved Space

  • Reserve the maximum space for each tuple

Variable-Length Space

• Pack tuples tightly
• Q: How do we know the end of a tuple?
  • At the end of the tuple, we add an "end" marker (Like null byte in C)
  • Store the length of the tuple
• What to do for delete/update?
  • Modify in place and shift everything back (slow)
  • Delete the original tuple and add the modified one at the back → issue of fragmentation
• How can we "point to" to a tuple?
  • We need block#, the beginning location of tuple

Slotted Page