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Aporeon interview preparation

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Performance

Execution plans, SARGability, indexes, N plus one queries, statistics, and reporting workload tuning.

7 drillsPractice one at a timeOrdered pathDebugging scenarioConcept question

Recommended start

Execution Plan Diagnosis

Uses an actual execution plan, row-flow evidence, runtime measurements, and representative parameters to diagnose a slow query without guessing.

Hard~12 minStep 1 of 7

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1Execution Plan DiagnosisRecommended startUses an actual execution plan, row-flow evidence, runtime measurements, and representative parameters to diagnose a slow query without guessing.Debugging scenarioHard~12 minSQLSQL ServerPractice 2

Practice order

7 drillsOne at a time

1Execution Plan DiagnosisUp next / Hard / ~12 min
2SARGabilityMedium / ~7 min
3Covering IndexesMedium / ~7 min
4

SARGability

Writes predicates the optimizer can use as index search arguments, then proves the effect through plans and reads while balancing computed columns, composite indexes, and write overhead.

Concept questionMedium~7 minSQLSQL Server

Practice

3Covering IndexesDesigns a narrow covering index from predicates and ordering, then weighs eliminated lookups against storage, write overhead, cache efficiency, overlap, and maintenance cost.Concept questionMedium~7 minSQLSQL ServerPractice

4N Plus One QueriesExplains N plus one query behavior, symptoms in APIs, fixes with set-based reads, batching, projections, and monitoring.Concept questionMedium~7 minEF CoreSQLSQL ServerPractice

5Statistics and PlansExplains how statistics and cardinality estimates affect plan choice, joins, memory grants, and slow queries.Concept questionHard~9 minSQLSQL ServerPractice

6Parameter SniffingExplains parameter sniffing, data skew, cached plans, symptoms, and cautious mitigation options in SQL Server.Concept questionHard~9 minSQLSQL ServerPractice

7Reporting vs OLTPProtects transactional traffic from reporting load through freshness requirements, bounded asynchronous jobs, tuned summaries, workload isolation, replicas or warehouses, and explicit capacity gates.Concept questionHard~9 minSQLSQL ServerPractice

N Plus One Queries

Medium / ~7 min

5Statistics and PlansHard / ~9 min

6Parameter SniffingHard / ~9 min

7Reporting vs OLTPHard / ~9 min

Performance - Database SQL | Aporeon