Questions from Database Systems

Q: Since pointers in a block chain include a cryptographic hash of the

Since pointers in a block chain include a cryptographic hash of the previous block, why is there the additional need for replication of the block chain to ensure immutability?

Q: Describe at least three tables that might be used to store information

Describe at least three tables that might be used to store information in a social- networking system such as Facebook.

Q: Write a servlet and associated HTML code for the following very simple

Write a servlet and associated HTML code for the following very simple application: A user is allowed to submit a form containing a value, say n, and should get a response containing n “*” symbols.

Q: Suppose a user forgets or loses her or his private key?

Suppose a user forgets or loses her or his private key? How is the user affected?

Q: Consider the library database of Figure 3.20. Write the

Consider the library database of Figure 3.20. Write the following queries in SQL. a. Find the member number and name of each member who has borrowed at least one book published by “McGraw-Hill”. b. Fi...

Q: How is the difficulty of proof-of-work mining adjusted

How is the difficulty of proof-of-work mining adjusted as more nodes join the network, thus increasing the total computational power of the network? De- scribe the process in detail.

Q: Why is Byzantine consensus a poor consensus mechanism in a public block

Why is Byzantine consensus a poor consensus mechanism in a public block chain?

Q: Explain how off-chain transaction processing can enhance throughput. What

Explain how off-chain transaction processing can enhance throughput. What are the trade-offs for this benefit?

Q: Choose an enterprise of personal interest to you and explain how block

Choose an enterprise of personal interest to you and explain how block chain technology could be employed usefully in that business.

Q: Rewrite the where clause Where unique (select title from course

Rewrite the where clause Where unique (select title from course) Without using the unique construct.