Alibaba ACA-Developer Exam - Topic 12 Question 105 Discussion

Question

When you use SQL statements to access tables in a database without an index configured, a full table scan will be performed. If a table contains a large amount of data, this kind of scan will access a large amount of data and consume a lot of the database's resources. Which of the following options are best practices when creating database indexes? (Number of correct answers: 3)

Cherri · Accepted Answer

A) Add an index to a field that is frequently queried but does not frequently perform add, delete, or modify operations. and B) Applies indices to fields that contain many records. and D) Apply indexing to fields of fixed length (preferably not long fields).

Cherri · Answer

C) table should not contain more than 6 indexed fields.

Cherri · Answer

E) Adhere to the rightmost prefix principle when using composite indexes.