Information Technology Reference
In-Depth Information
Problems
4.1 At the time of a system failure, the log surviving on the log disk contains the
following records:
101: h begin-checkpoint i
102: h active-transaction-table ; fgi
103: h modified-page-table ; fgi
104: h end-checkpoint i
105: h T 1 ;B i
106: h T 1 ;I;p;x 1 ; v 1 ; 105 i
107: h T 2 ;B i
108: h T 2 ;I;p;x 2 ; v 2 ; 107 i
109: h allocate-page-for-heap ;s;f;p;q i
110: h T 1 ;I;q;x 3 ; v 3 ; 106 i
111: h T 2 ; S ŒP ; 108 i
112: h T 2 ;I;q;x 4 ; v 4 ; 111 i
113: h T 1 ;I;q;x 5 ; v 5 ; 110 i
114: h T 2 ;I;q;x 6 ; v 6 ; 112 i
115: h T 2 ;AŒP i
116: h T 2 ;I 1 ;q;x 6 ; 112 i
117: h T 3 ;B i
118: h T 3 ;I;q;x 7 ; v 7 ; 117 i
119: h T 1 ;C i
None of the pages updated (s, f , p, q) were flushed onto disk after the updates
logged with LSN s 106-118. The structure modification logged with LSN 109 uses
space-map page s to allocate a new page q and assigns the page-id p into the last-
page link field in the first page, f , of the heap and in the next-page link field in the
last page, p, of the heap. The allocation is triggered by an attempt by transaction T 1
to insert a tuple, .x 3 ; v 3 /,intopagep, which turns out to be full; the insertion goes
to the allocated page q.
The ARIES recovery algorithm is used to recover the system from the failure.
(a) What actions are involved in the analysis pass of ARIES ?Atwhat LSN does the
log scan begin? What are the contents of the active-transaction table and the
modified-page table reconstructed in the analysis pass? What is the value set to
the R EDO -LSN ?
(b) What actions are involved in the redo pass of ARIES ?Atwhat LSN does the log
scan begin? When are pages latched and unlatched and what is done on those
pages? What are the P AGE -LSN values of the current versions of the pages s, f ,
p,andq at the end of the redo pass? No pages are flushed onto disk during the
redo pass.
(c) What actions are involved in the undo pass of ARIES ? We assume that all undo
actions can be performed physically. What log records are generated? What are
the P AGE -LSN values of the current versions of the pages s, f , p,andq at the
end of the redo pass?
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