Self doubt

Question

Which of the following are RECOVERABLE schedules

Comments

I dont know exact answer so I asked..

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ALL ARE RECOVERABLE RIGHT ????

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@Balaji Jegan @Shaik Masthan

Answer 1

I think that all of them are recoverable because if a transaction Ti reads a value written by transaction Tj then Tj should commit before Ti.

If Ti commits first and error occurs before commitment of Tj then it will not be possible to redo Ti.

So in above question, T2(Which is reading value written by T1) is not committing in any of the case, so we can redo it if error occurs.