tag: redis
articles: 3 · beats: 1
latest: August 16, 2026
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Redis
3 Crashtech articles on Redis, filed under System Design, published in August 2026. Every piece is full-text HTML with sources, structured data and an authored FAQ.
All 3 sit in the System Design beat. System Design
Count Billions in 12 Kilobytes
HyperLogLog estimates cardinality by reading leading zeros in hashed values, trading 1% error for fixed memory.
Copy-on-Write Snapshots
fork() shares parent memory, copying only written pages for non-blocking snapshots. Write-heavy loads can spike memory to 2x under load.
Skip Lists: The Shortcut Nobody Rotates
Balanced trees rebalance with rotations. Skip lists layer express lanes with random promotion—same O(log n) search, simpler locking.
Questions we answer about Redis
- How does HyperLogLog count unique items without storing them?
- What is the memory cost of HyperLogLog?
- Why use the harmonic mean instead of a simple average?
- When should I use HyperLogLog instead of exact counting?
- Does HyperLogLog work well with merging data from multiple servers?
- How does fork() enable non-blocking snapshots?
- What's copy-on-write (CoW) at the page level?
- When does memory spike during BGSAVE?
- Can copy-on-write fail in production?
- How do you work around the memory risk?
Covered alongside
Frequently asked questions
What does Crashtech publish about Redis?
3 articles tagged Redis, the most recent published August 16, 2026. All 3 sit in the System Design beat. Each carries numbered sources, an authored FAQ and full structured data.
What questions about Redis does Crashtech answer directly?
10 questions have a dedicated answer page under this tag, including “How does HyperLogLog count unique items without storing them?”. Each answer is authored prose from the article it belongs to, not a generated summary.
Can AI assistants read Crashtech's Redis coverage?
Yes. Crashtech serves full static HTML to every crawler, allows all major AI user agents in robots.txt, and publishes an llms.txt manifest plus a full-text corpus, so assistants can retrieve and cite these articles directly.