Postgresql easy
PostgreSQL records all data changes in a Write-Ahead Log (WAL) before updating data files. What is the primary operational benefit?
- A It allows the database to skip individual row-level locks for every single write request.
- B It ensures durability and crash recovery by allowing recent changes to be replayed.
- C It provides a mechanism for real-time data compression of the main table heap files.
- D It creates a searchable audit log that tracks the IP address of every connected user.
Answer: B. It ensures durability and crash recovery by allowing recent changes to be replayed.
WAL is critical for ACID compliance. Since the log is updated sequentially before the more expensive random I/O of data file updates, the database can safely recover its state even if power is lost mid-transaction.
One system design question a day, with spaced repetition so the ones you miss come back.
Get the appRelated questions
- In a PostgreSQL environment, what functional characteristic distinguishes a `MATERIALIZED VIEW` from a standard `VIEW`?
- Which standard PostgreSQL utility is designed to extract a single database into a script or archive file for backup purposes?
- Why would PostgreSQL reject a `DELETE` operation on a record despite the user having full administrative privileges?
- The 'Heap Only Tuples' (HOT) optimization improves UPDATE performance. Which specific set of conditions must be met for a HOT update to occur?
- Which native command-line utility is used to execute SQL queries and manage PostgreSQL databases from a terminal session?
- What is the specific purpose of 'Freezing' a row (modifying its `xmin` status) during a major VACUUM operation?