Which of the following is false about replication
good idea to ensure that all conflicting operations done in same order everywhere
guaranteeing global ordering on conflicting operations may be costly, downgrading scalability
replication can greatly increase performance of non-conflicting operations
Weakening consistency requirements to increases global synchronization requirements
Does this conform to sequential consistency?
Which of the following definitions are correct:
Read Your Writes: Effect of write operation by process on data item x, always seen by successive read operation on x by same process
Writes Follow Reads: Write operation by process on data item x following previous read operation on x by same process is guaranteed to take place on same or more recent value of x that was read.
Read write read: Write operation by process on data item x following previous read operation on x by same process is guaranteed to take place on same or more recent value of x that was read.
Read Your Writes: Write operation by process on data item x following previous read operation on x by same process is guaranteed to take place on same or more recent value of x that was read.
Which of the following is not a Data-Centric Consistency Model
Read-your-writes Consistency
Sequential Consistency
Causal Consistency
Eventual consistency
Which of the following is false about Object aware of replication
More difficult for developers
Allows for application specific solutions
Middleware handles communication
Middleware is responsible for ensuring objects are consistent across nodes
Which of the following is true about Monotonic reads and writes?
If process reads value of data item x, any successive read operation on x by that process will always return that same or more recent value
Write operation by process on data item x completed before any successive write on x by same process
If process reads value of data item x, any successive read operation on x by that process will always return a value no older than the latency between the client and the server
Write operation by process on data item x completed before any successive write by other users in the system
Does this conform to casual consistency?
Which of the following is not an advantage of replication?
Increase availability
Enhance reliability
Improve performance
Improved data consistency
Which of the following is false about eventual consistency?
Database must tolerate a high degree of inconsistency
Updates guaranteed to propagate to all replicas
if no updates for long time, all replicas gradually become consistent
Eventual consistency increases the time an insert operation takes
In Gifford's scheme, which of the following is true
To prevent read-write conflicts: Nr + Nw > N
To prevent write-write conflicts: Nw > N/2
To prevent read-write conflicts: Nw > N/2
To prevent write-write conflicts: Nr + Nw > N + 1
Which of the following is false about pull vs. push update protocols
Push: Server must have list of replicas
Push: No polling required
Pull: Updates are immediate
Pull: Polling required
Does this conform to strict consistency?
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