Message 18

FYI, on allocate_page() and deallocate_page() --

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Date: Fri, 21 Sep 2001 14:38:50 -0400 (EDT)
From: Leejay Wu <lw2j+@andrew.cmu.edu>
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To: Andrew BBoard Account <bb+academic.cs.15-721@andrew.cmu.edu>
Subject: FYI, on allocate_page() and deallocate_page() --
Cc: 

They do call your pinPage() and unpinPage() functions, and here's why --

The database uses one or more pages to track whether or not disk
pages are in use -- and only whether they are in use, not who is
using them.  Thus, a bitmap is stored, where 0 means free and 1
is in-use.

To allocate or free a page, then, the buffer manager is called to
bring one or more bitmap pages into memory, one at a time.
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