PostgreSQL вопросы и ответы для интервью
Вопрос 11. Explain the purpose of the SERIAL data type in PostgreSQL.
SERIAL is an auto-incrementing integer data type often used for creating unique identifiers in a column. It is commonly used for primary key columns.
Вопрос 12. What is a view in PostgreSQL, and how is it different from a table?
A view is a virtual table based on the result of a SELECT query. It does not store the data itself but provides a way to represent data stored in one or more tables. Unlike a table, a view does not store data physically.
Вопрос 13. How do you perform a backup and restore in PostgreSQL?
You can use the pg_dump utility to create a backup and the pg_restore utility to restore the database from a backup file. Additionally, you can use the pg_basebackup tool for physical backups.
Вопрос 14. What are common indexing techniques in PostgreSQL, and when should they be used?
Common indexing techniques include B-tree, Hash, and GiST indexes. They should be used to improve query performance, especially for columns frequently used in WHERE clauses or JOIN conditions.
Вопрос 15. Explain the difference between VACUUM and ANALYZE in PostgreSQL.
VACUUM is used to reclaim storage occupied by dead tuples, while ANALYZE is used to update statistics about the distribution of data in a table, helping the query planner make better decisions.
Самое полезное по оценкам пользователей:
- Explain the concept of ACID properties in the context of databases.
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- What is a foreign key, and how does it enforce referential integrity?
- Explain the purpose of the SERIAL data type in PostgreSQL.