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Apr 18 In-Class Exercise Thread.

Post your solutions to the Apr 18 In-Class Exercise Thread.

Best,

Chris

Post your solutions to the Apr 18 In-Class Exercise Thread. Best, Chris

-- Apr 18 In-Class Exercise Thread

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-- Apr 18 In-Class Exercise Thread

1. `S -> R_S(X) -> W_S(X) -> C -> T -> W_T(X)`, RT(X) = TS(S), WT(X) = TS(S)

2. `T -> S -> R_T(X) -> C -> W_T(X)`

-Casey

(Edited: 2018-04-18)

1. @BT@S -> R_S(X) -> W_S(X) -> C -> T -> W_T(X)@BT@, RT(X) = TS(S), WT(X) = TS(S) 2. @BT@T -> S -> R_T(X) -> C -> W_T(X)@BT@ -Casey

-- Apr 18 In-Class Exercise Thread

Let T and S be our transactions

 1. TS(T) ≥ RT(X) and TS(T) ≥ WT(X)
	S---Rs(X)---Ws(X)---Cs---T---Wt(X)
		(RTime(X) = TS(S))
		(WTime(X) = TS(S))

 2. TS(T) ≥ RT(X) but TS(T) < WT(X)
	S---Rs(X)---Cs---T---U---Wu(X)---Wt(X)
		(RTime(X) = TS(S))

(Edited: 2018-04-18)

Let T and S be our transactions 1. TS(T) ≥ RT(X) and TS(T) ≥ WT(X) S---Rs(X)---Ws(X)---Cs---T---Wt(X) (RTime(X) = TS(S)) (WTime(X) = TS(S)) 2. TS(T) ≥ RT(X) but TS(T) < WT(X) S---Rs(X)---Cs---T---U---Wu(X)---Wt(X) (RTime(X) = TS(S))

-- Apr 18 In-Class Exercise Thread

 1. START S, R_S(X), W_S(S) COMMIT S, START T, W_T(X)
 2. START S, R_S(X), START T, COMMIT S, START U, W_U(X), COMMIT U, W_T(X)

(Edited: 2018-04-18)

1. START S, R_S(X), W_S(S) COMMIT S, START T, W_T(X) 2. START S, R_S(X), START T, COMMIT S, START U, W_U(X), COMMIT U, W_T(X)

-- Apr 18 In-Class Exercise Thread

1. Start(S), RS(X), WS(X), Start(T), WT(X)

2.Start(S), RS(X), Start(T), Start(Z), WZ(X)

Elena

(Edited: 2018-04-18)

1. Start(S), RS(X), WS(X), Start(T), WT(X) 2.Start(S), RS(X), Start(T), Start(Z), WZ(X) Elena

-- Apr 18 In-Class Exercise Thread

Let there be two transactions T and U running concurrently (lowercase letters u and t beside R and W are subscript):

1) <Start U> --> <Ru(X)> --> <Wu(X)> --> <Commit U> --> <Start (T)> --> <Wt(X)> --> <Commit T> // When T starts, timestamp for both Read x and Read y are before transaction T has started.

2) <Start U> --> <Ru(X)> --> <Start T> --> <Wu(X)> --> <Commit U> --> <Wt(X)> --> <Commit T> // Wt(X) must occur after U commits so delay T until U is over.

(Edited: 2018-04-18)

Let there be two transactions T and U running concurrently (lowercase letters u and t beside R and W are subscript): 1) <Start U> --> <Ru(X)> --> <Wu(X)> --> <Commit U> --> <Start (T)> --> <Wt(X)> --> <Commit T> // When T starts, timestamp for both Read x and Read y are before transaction T has started. 2) <Start U> --> <Ru(X)> --> <Start T> --> <Wu(X)> --> <Commit U> --> <Wt(X)> --> <Commit T> // Wt(X) must occur after U commits so delay T until U is over.

-- Apr 18 In-Class Exercise Thread

1) `START(S), R_s(X), W_s(X), Commit, START(T), W_T(X)`

2) `START(S), R_S(X), START(T), T_Z(X), W_Z(X), W_T(X)`

(Edited: 2018-04-18)

1) @BT@START(S), R_s(X), W_s(X), Commit, START(T), W_T(X)@BT@ 2) @BT@START(S), R_S(X), START(T), T_Z(X), W_Z(X), W_T(X)@BT@

-- Apr 18 In-Class Exercise Thread

1. S starts, `R_S(X), W_S(X), C_S,` T starts,` W_T(X)`
2. S starts, `R_S(X), C_S,` T starts, `W_T(X), C_T`

(Edited: 2018-04-18)

1. S starts, @BT@R_S(X), W_S(X), C_S,@BT@ T starts,@BT@ W_T(X)@BT@ 2. S starts, @BT@R_S(X), C_S,@BT@ T starts, @BT@W_T(X), C_T@BT@

-- Apr 18 In-Class Exercise Thread

((resource:1524091636618748443961500004151.jpg|Resource Description for 1524091636618748443961500004151.jpg))