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LetsGit.IT/Categories/Data Structures
Data Structureshard

B-tree vs binary search tree — why are B-trees common on disk?

Tags
#b-tree#bst#disk-io#indexes
Back to categoryPractice quiz

Answer

B-trees have high branching factor, so they stay shallow and reduce disk IO (fewer page reads). BSTs are pointer-heavy and deep; they are good in memory but inefficient on disk compared to page-friendly B-trees.

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): b-tree, bst, disk-io, indexes
  • Complexity: compare typical operations (average vs worst-case).
  • Invariants: what must always hold for correctness.
  • When the choice is wrong: production symptoms (latency, GC, cache misses).
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "b-tree-vs-binary-search-tree-—-why-are-b-trees-c"
function explain() {
  // Start from the core idea:
  // B-trees have high branching factor, so they stay shallow and reduce disk IO (fewer page re
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?

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