[prev] 55 [next]

Buffer Pool (cont)

Buffer pool data structures:
  • a fixed-size, memory-resident collection of frames (page-slots)
  • a directory containing information about the status of each frame
For each frame, we need to know:
  • contents = PageId (dbid,relid,page#) or Empty flag (tag)
  • whether it has been modified since loading (dirty bit)
  • how many transactions are currently using it (pin count)
  • time-stamp for most recent access (assists with replacement)
  • pointer to next free frame (free list)