Top 50 database optimization Interview Questions
The most frequently asked database optimization questions across all roles and companies, ranked by real interview frequency. Updated daily.
Optimize a slow PostgreSQL query that aggregates completed transactions while preserving customers with no matching activity.
Capgemini
NomuraExplain how to diagnose a slow SQL query and improve its performance.
Aubay SpainWrite a selective PostgreSQL ticket query and explain how indexing can improve its filtering and sorting performance.
Zendesk
FactoredBuild an efficient PostgreSQL report that aggregates partitioned project events and costs without join multiplication.
McKinsey &Detect a heavily skewed join key and produce a deterministically salted join result for more balanced large-scale processing.
DatabricksAggregate qualifying customer events across shards efficiently while joining customer details and excluding low-volume results.
AdobeOptimize a large Apple analytics query using partition pruning, selective indexes, joins, aggregation, and window calculations.
AppleOptimize a PostgreSQL query with multiple joins and aggregations over large tables while preserving correct filtered totals.
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