Shadow Paging in database management system free pdf notes
1. If the ith page (that is, the page on which X resides) is not already in main memory, then the system issues input(X).
2. If this is the write first performed on the ith page by this transaction, then the system modifies the current page table as follows:
a. It finds an unused page on disk. Usually, the database system has access to a list of unused (free) pages.
b. It deletes the page found in step 2a from the list of free page frames; it copies the contents of the ith page to the page found in step 2a.
c. It modifies the current page table so that the ith entry points to the page found in step 2a.