SQL Optimization Best Practices

Introduction

A consolidated checklist used by senior engineers to keep databases fast — at small and large scale.

Understanding the topic

Core concepts to understand:

• Always have a primary key & FK indexes.
• Add the right indexes for your top queries.
• EXPLAIN ANALYZE before & after changes.
• Use connection pooling (pgBouncer, ProxySQL).
• Monitor pg_stat_statements / slow log weekly.
• Keep statistics fresh (ANALYZE / autovacuum).
• Cache smartly; invalidate carefully.
• Bulk insert/update; never N+1.

Syntax reference

Visual workflow / architecture:

Daily checklist
 □ Slow query review
 □ Top write hot tables
 □ Replication lag
 □ Disk usage
 □ Long-running transactions

Real-world use

Every healthy production DB team runs through this kind of checklist — daily, weekly and during incidents.

Best practices

• Make perf a routine, not a fire drill.
• Document tuning changes.
• Set SLOs on query latency.

Hands-on exercise

Interview preparation — practice these questions:

• Q1. Top 5 SQL perf practices.
• Q2. How often do you run ANALYZE?
• Q3. Connection pool — why?
• Q4. SLOs you've set on DB.
• Q5. Last perf incident & fix.