FORCE:

Whenever a transaction Ti wants to commit:

   1. flush the log to disk

   2. Write all the pages modified by Ti

   3. Write commit record for Ti to log, flush the log to disk

   4. Allow Ti to commit







NO FORCE:

Whenever a transaction Ti wants to commit:

   1. Write the commit record for Ti and flush the log to disk

   2. Allow Ti to commit



(*) Pages modified by the transaction will be written to disk by the
    DBMS as needed/not needed by other transactions









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STEAL:

Whenever a transaction wants to use a memory block allocated to a
page modified by an uncommited transaction:

    1. Flush the log (Write Ahead Logging)

    2. Write the modified page to disk and free up memory
    it occupied




NO STEAL:

Pin all memory blocks occupied by an uncommitted transaction
and keep all dirty pages in memory until transaction commits.