18 terms

two-phase locking protocols

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two phase locking protocol 1
basic
two phase locking protocol 2
conservative
two phase locking protocol 3
strict
two phase locking protocol 4
rigorous
two phase locking protocol 5
ordering all items
2pl basic 1
growing phase (acquire locks without releasing locks)
2pl basic 2
shrink phase (release locks without acquiring locks)
2pl conservative
acquire all locks before execution begins (dead lock free)
2pl strict
release write locks only after commit/abort
2pl rigorous
release read and write locks only after commit/abort
2pl ordering all the items
order all the items needed and lock them according to that order (not practical)
deadlock prevention protocols with timestamp
wait-die and wound-wait
deadlock prevention protocols without timestamp
no waiting and cautious waiting
wait-die
Can I lock an item?
If not, am I older than the transaction holding that item?
If so, I must die
Otherwise I will wait
wound-wait
Can I lock an item?
If not, am I older than the transaction holding that item?
If so, I must kill you and continue.
no waiting
I just abort myself and retry
cautious waiting
is intelligent. I requested an item. Item is engaged in something else. I look at that item and see what transaction has it. If that transaction waiting, I abort and retry. If that transaction not waiting, I wait.
Any schedule that follows 2 phase locking is guaranteed to be ....
conflict serializable
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