2 Phase Locking

Question

Consider the following schedule:

S:R₂(A) W₁(B) W₁(C) R₃(B) R₂(B) R₁(A) C1 R₂(C) C2 W₃(A)C3

Please explain how it is allowed in 2 PL

Comments

hahaha :)

i jused used camscanner app to click image, the app directly convert clicked image into pdf.

---

use Adobe scanner instead, that will saturate image more accurately while converting to pdf :p

---

the above schedule is conflict serializable hence it will definetly allowed by 2PL

Answer 1

T1	T2	T3
	S(A)
	R(A)
X(B)
X(C)
W(B)
W(C)
S(A)
U(B)
U(C)
		S(B)
		R(B)
	S(B)
	R(B)
R(A)
U(A)
	S(C)
	R(C)
	U(A)
	U(B)
	U(C)
		X(A)
		W(A)
		U(A)
		U(B)

Comments

T1	T2	T3
	S(A)
	R(A)
X(B)
X(C)
W(B)
W(C)
S(A) U(B) U(C)
		S(B)
		R(B)
	S(B)
	R(B)
R(A)
C2 U(A)
	S(C)
	R(C)
	C2
	U(C)
	U(B)
		X(A)
		W(A)
		C3
		U(B)
		U(A)

---

why S(A) is taken so early in T1 ? can I take it just before R(A)??

---

No locking can be done only in growing phase