Choose the description that is incorrect regarding the differences between in-memory...
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Choose the description that is incorrect regarding the differences between in-memory databases and traditional databases like MySQL or PostgreSQL.
Show answer & explanation
Option B is incorrect because in-memory databases store data in volatile RAM, which is lost upon power failure or system crash—making them more vulnerable to data loss, not more resilient. Traditional disk-based databases persist data to HDDs/SSDs, providing durability against hardware failure. Options A, C, and D are all correct: in-memory DBs are faster (no disk I/O), rely on capacity management strategies like eviction policies rather than just adding RAM, and Redis/Memcached are standard examples.
Step-by-step Derivation:
Analyze each statement:
- A) TRUE: In-memory databases access data from RAM (
100ns latency) vs. disk access (10ms), making them significantly faster. - B) FALSE: In-memory databases lose all data on power loss or crash because RAM is volatile. Disk-based DBs persist to SSD/HDD, making them more resilient to physical failures.
- C) TRUE: In-memory DBs use eviction policies (LRU, LFU) and TTL to manage limited RAM when data exceeds capacity—not just throwing more memory at it.
- D) TRUE: Redis and Memcached are canonical in-memory database examples.
The question asks for the incorrect statement, which is B.