Real case questions-database system

Expansion mode and horizontal expansion are the same thing.
Relational database is strong in upward expansion, but weak in horizontal expansion (outward expansion).
NoSQL mode is weak in upward expansion, but strong in horizontal expansion (outward expansion).

Scaling up means adding databases.
Scaling out means dividing the database and storing it in different databases.

Data consistency and transactions also correspond to
real-time consistency – high transactionality,
weak consistency – weak transactionality

If you need to modify it, add a write lock. If you don't want to modify it, add a read lock. If
you add a read lock, you can only add a read lock.

T1 write lock
T2 write lock

T1 read lock
T2 write lock

T1 write lock
T2 read lock

Real questions

Question 1

Data independence
Control structure that combines centralization and autonomous sharing Appropriate
increase in data redundancy
Global consistency, serializability, recoverability


Directly select the opposite,,, in the table

Question 2

Question 3