GATE Papers >> CSE >> 2019 >> Question No 21

Question No. 21 CSE | GATE 2019

Consider the following two statements about database transaction schedules:

I.  Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable.

II. Timestamp-ordering concurrency control protocol with Thomas’ Write Rule can generate view serializable schedules that are not conflict serializable.

Which of the above statements is/are TRUE?


Answer : (C) Both I and II


Solution of Question No 21 of GATE 2019 CSE Paper

(I) 2PL is conflict Serializable then we can say strcit 2PL also cinflict serializable.

    In strict 2PL exclusive locks will be unlocked after commit because of this, there may not be dirty read. If there is no dirty read then we cansay it is recoverable.

    Statement (I) is true

(II)Thomas write rule using this user can achieve view serializable schedules, and it ignores obsolete writes so here it generates view serializable which is not conflict serializable

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