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Serializable Schedule Definition

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jcalilu Posts: 20	Posted 20:04 May 25, 2016 \| In the powerpoint for concurrency, slide #10, it says "A serializable schedule is a schedule that produces the same result as some serial schedule" My question is when it says same result, does it mean it has to be exactly of the form T₁T₂ or T₂T₁(definition of serial schedule)? For example in slide # 11 for concurrency, r₁(x), w₁(x), r₂(y), w₂(y), r₁(y), w₁(y), w₂(x) so is this schedule not serializable since it is not in the form T₁T₂ or T₂T₁? Last edited by jcalilu at 20:04 May 25, 2016.
cysun Posts: 2935	Posted 20:22 May 25, 2016 \| "same result" as a serial schedule doesn't mean being a serial schedule. For example, suppose T1: r1(x) and T2: r2(x),w2(x), then the schedule r2(x),r1(x),w2(x) is not serial (i.e. neither T1T2 nor T2T1), but it's serializable because the "result" is the same as T1T2.

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jcalilu

Posts: 20

Posted 20:04 May 25, 2016 |

In the powerpoint for concurrency, slide #10, it says

"A serializable schedule is a schedule that produces the same result as some serial schedule"

My question is when it says same result, does it mean it has to be exactly of the form T₁T₂ or T₂T₁(definition of serial schedule)?

For example in slide # 11 for concurrency,

r₁(x), w₁(x), r₂(y), w₂(y), r₁(y), w₁(y), w₂(x)

so is this schedule not serializable since it is not in the form T₁T₂ or T₂T₁?

Last edited by jcalilu at 20:04 May 25, 2016.

cysun

Posts: 2935

Posted 20:22 May 25, 2016 |

"same result" as a serial schedule doesn't mean being a serial schedule. For example, suppose T1: r1(x) and T2: r2(x),w2(x), then the schedule r2(x),r1(x),w2(x) is not serial (i.e. neither T1T2 nor T2T1), but it's serializable because the "result" is the same as T1T2.