**ACID**: Atomicity (all or nothing), Consistency (valid state), Isolation (concurrent transactions), Durability (persisted). **Why in data**: Traditional lakes lacked ACIDâconcurrent writes corrupted data. Delta Lake, Iceberg provide ACID via transaction logs: concurrent...
Pro-Move: 'We use Delta for our curated layerâMERGE for upserts, time travel for incident recovery; Iceberg for cross-engine.' Red Flag: Saying 'we don't need ACID' for financial or compliance dataâyou do.
This easy-level General/Other question appears frequently in data engineering interviews at companies like Presidio. While less common, it tests deeper understanding that distinguishes strong candidates.
Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.
ACID: Atomicity (all or nothing), Consistency (valid state), Isolation (concurrent transactions), Durability (persisted). Why in data: Traditional lakes lacked ACIDâconcurrent writes corrupted data. Delta Lake, Iceberg provide ACID via transaction logs: concurrent writes, time travel, schema evolution. Use cases: Exactly-once processing, compliance, financial. Trade-off: ACID adds metadata overhead; traditional append-only is simpler but can't update/merge. Best practice: Use Delta or Iceberg when you need updates, deletes, merges.
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According to DataEngPrep.tech, this is one of the most frequently asked General/Other interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.