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The strict two-phase locking (S2PL) class of

schedules is the intersection of the 2PL class with the

class of schedules possessing the Strictness property.

To comply with the S2PL protocol a transaction

needs to comply with 2PL, and release its write

(exclusive) locks only after it has ended, i.e., being

either committed or aborted. On the other hand, read

(shared) locks are released regularly during phase 2.

Implementing general S2PL requires explicit support

of phase-1 end, separate from transaction end, and no

such widely utilized product implementation is

known.

S2PL is a special case of 2PL, i.e., the S2PL class is a

proper subclass of 2PL

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What benefits does strict two phase locking provide and What disadvantages result?

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