Question

Q7 0.25 Points What is a "dirty read"? Which desirable property of transactions is compromised if dirty reads are allowed (even if serializability is guaranteed)? Q8 0.25 Points Say there is a B+-tree primary index on a relation R. Since an insert or a delete into R changes the index as well, we must take locks on the index during updates. Briefly explain what kind of locks you would take on the index pages when doing an insert or a delete into the relation. Remember a page split or merge may involve the ancestors and the siblings of a node. Q9 0.25 Points The main difference between strict 2PL and rigorous 2PL is that -- for the latter, the serializability order is the same as the commit order (i.e., if you were to draw a precedence graph and find the serial schedule -- it would be the same as the order in which the transactions committed. Show through an example how this is not true for Strict 2PL. That is: provide an example schedule that follows Strict 2PL, but the serializability order is different from the commit order.

          Q7
0.25 Points
What is a "dirty read"? Which desirable property of transactions is compromised if dirty reads
are allowed (even if serializability is guaranteed)?
Q8
0.25 Points
Say there is a B+-tree primary index on a relation R. Since an insert or a delete into R changes
the index as well, we must take locks on the index during updates. Briefly explain what kind of
locks you would take on the index pages when doing an insert or a delete into the relation.
Remember a page split or merge may involve the ancestors and the siblings of a node.
Q9
0.25 Points
The main difference between strict 2PL and rigorous 2PL is that -- for the latter, the
serializability order is the same as the commit order (i.e., if you were to draw a precedence
graph and find the serial schedule -- it would be the same as the order in which the transactions
committed. Show through an example how this is not true for Strict 2PL. That is: provide an
example schedule that follows Strict 2PL, but the serializability order is different from the
commit order.

Q7
0.25 Points
What is a "dirty read"? Which desirable property of transactions is compromised if dirty reads
are allowed (even if serializability is guaranteed)?
Q8
0.25 Points
Say there is a B+-tree primary index on a relation R. Since an insert or a delete into R changes
the index as well, we must take locks on the index during updates. Briefly explain what kind of
locks you would take on the index pages when doing an insert or a delete into the relation.
Remember a page split or merge may involve the ancestors and the siblings of a node.
Q9
0.25 Points
The main difference between strict 2PL and rigorous 2PL is that – for the latter, the
serializability order is the same as the commit order (i.e., if you were to draw a precedence
graph and find the serial schedule – it would be the same as the order in which the transactions
committed. Show through an example how this is not true for Strict 2PL. That is: provide an
example schedule that follows Strict 2PL, but the serializability order is different from the
commit order.

Added by Carla V.

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