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BufferPool
Qian(Christina) Wang edited this page Oct 31, 2016
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Pin_Count: The number of times that the page currently in a given frame has been requested but not released-the number of current users of the page--isrecorded in the pin_count variable for that frame. Dirty: Since the page have been brought in the bufferpool whether it have been modified
If existed in buffer pool: return
If not in buffer pool:
- choose a replacement frame(using replacement policy) and +pin_count
- if the chosen replacement frame is dirty, write back to disk
- reads the requested page into frame.
- Returns the** (main memory) **address of the frame containing the requested page to the requestor.
The locking protocol ensures that each transaction obtains a shared or exclusive lock before requesting a page to read or modify.