4.10.5 Client server databases

Question 1

What is a client server database system?

Answer 1

Provides simultaneous access to the database for

multiple clients.

Question 2

What is concurrent access?

Answer 2

Concurrent access can result in the problem of
updates being lost if two clients edit a record at
the same time. Multiple users editing the database puts the database at risk (integrity)

Question 3

How are record locks used?

Answer 3

The first person to open the record gets write access, the other people only get read access. Used in networks with documents with shared access

Question 4

How is serialisation used?

Answer 4

Only allowing transactions to take place one at a time - every request to edit the database is done one at a time

Question 5

How is timestamp ordering used?

Answer 5

Every transaction has a read and write timestamp, used to sequence transactions as you may be updating something that has already been updated since you requested it
Requires more data to be stored in the server

Question 6

How is commitment ordering used?

Answer 6

Requests have different priorities, by analysing the commands, e.g write requests would have higher priority than read