Question $1$:

a$)$ Consider the log below; show all the actions of a recovery manager after the crash

$T1,A,$ update, $5,10$

$T2,B,$ update, $2,4$

$T1,A,$ update, $10,20$

$T2,B,$ update, $4,5$

T$3,$ C$,$ update, $2,3$

T$3,$ commit

T$2,$ commit

CRASH

b$)$ What actions must the DBMS take, in what order, to abort T$1?$

$T1,A,$ update, $100,200$

$T1,A,$ update, $200,100$

$T2,D,$ update, $500,1000$

$T1,B,$ update, 'ABC' $,$ 'DEF'

$T1,$ abort