PostgreSQL, often referred to as Postgres, is a powerful open-source relational database management system (RDBMS) known for its scalability, robustness, and extensibility. It offers advanced features like ACID compliance, support for complex data types, and support for both SQL and NoSQL data. PostgreSQL is highly regarded for its performance, security, and reliability, making it a popular choice for applications ranging from small startups to large enterprises. Its active developer community continuously enhances and maintains the software. PostgreSQL is an excellent choice for data storage, analysis, and management in various domains, including web applications, data warehousing, and geospatial applications.
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Practice Test
71. What is the purpose of the "EXPLAIN" command in PostgreSQL?
A. To analyze the execution plan of a SQL query
B. To create a new database
C. To optimize the storage of large tables
D. To create a new index
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Answer: To analyze the execution plan of a SQL query
72. In PostgreSQL, what does the term "index" refer to in the context of performance tuning?
A. A data structure that provides quick access to specific columns
B. A special table that stores summary information
C. A file used for database backups
D. A data type used for storing integers
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Answer: A data structure that provides quick access to specific columns
73. What is an "auto-vacuum" in PostgreSQL, and how does it relate to performance tuning?
A. A process that automatically reclaims storage and optimizes table maintenance
B. A type of index that automatically reorders data
C. A feature that generates SQL code for optimization
D. A background process for sorting data
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Answer: A process that automatically reclaims storage and optimizes table maintenance
74. What is the purpose of "ANALYZE" in PostgreSQL's VACUUM command?
A. To update statistics about the table for query planning
B. To physically reorganize the table data
C. To delete old rows from the table
D. To lock the table for exclusive access
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Answer: To update statistics about the table for query planning
75. How can you improve query performance for a frequently used column in PostgreSQL?
A. Create an index on the column
B. Drop the column from the table
C. Increase the table's storage size
D. Change the column's data type
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Answer: Create an index on the column
76. What is the purpose of "connection pooling" in PostgreSQL performance tuning?
A. To reuse database connections, reducing connection overhead
B. To store data redundantly for backup
C. To combine multiple databases into a single pool
D. To increase the number of available connections
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Answer: To reuse database connections, reducing connection overhead
77. What is a "query planner" in PostgreSQL and how does it impact performance?
A. It generates query execution plans and can significantly affect query performance
B. It stores query results for future use
C. It optimizes the storage of large tables
D. It automatically tunes the database
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Answer: It generates query execution plans and can significantly affect query performance
78. What does the "shared_buffers" configuration parameter in PostgreSQL control?
A. The amount of memory allocated for caching data in shared memory
B. The size of individual table spaces
C. The number of connections allowed to the database
D. The maximum query execution time
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Answer: The amount of memory allocated for caching data in shared memory
79. What is "table partitioning" in PostgreSQL, and how can it improve performance?
A. Dividing a table into smaller, more manageable pieces
B. Joining multiple tables into one
C. Removing tables to reduce complexity
D. Increasing the number of indexes
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Answer: Dividing a table into smaller, more manageable pieces
80. What is the purpose of the "pg_stat_statements" module in PostgreSQL?
A. It tracks SQL statement execution and helps identify performance issues
B. It controls access to database objects
C. It generates SQL code for optimization
D. It encrypts data at rest
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Answer: It tracks SQL statement execution and helps identify performance issues
