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Performance & Query Reading
Just enough EXPLAIN, query performance, and indexing to read your own plans and write index-friendly SQL. You're not a DBA — but you should sound like you've met one.
Module Content
EXPLAIN for Analysts — Just Enough to Read One
You don't need to be a DBA. You need to recognize 5 patterns in an EXPLAIN plan that tell you why your query is slow. FIND_VIDEO: search 'EXPLAIN ANALYZE postgres tutorial analyst' — recommended channel: Crunchy Data / EverSQL. Aim for 10 min or under.
Recap — Five Things to Look For
A 5-bullet checklist for reading a Postgres EXPLAIN plan as an analyst, not a DBA.
The 5 Most Common Reasons Your SQL Is Slow
Walk through the five patterns that account for ~80% of slow analyst queries. FIND_VIDEO: search 'why is my SQL query slow common reasons' — recommended channel: EverSQL / Crunchy Data. Aim for 11 min or under.
Recap — The Query Performance Checklist
Five questions to ask any slow query. Most of the time, one of them is the answer.
CTE vs Subquery vs Temp Table — When to Use Each
Three patterns, three performance profiles. Most analysts pick one and use it for everything — wrong. FIND_VIDEO: search 'CTE vs subquery vs temp table performance' — recommended channel: Modern SQL. Aim for 10 min or under.
Recap — Choosing the Right Pattern
A decision tree for whether your intermediate result should be a CTE, a subquery, or a temp table.
Indexes for Analysts — What to Know
You're not a DBA. But knowing 6 index facts will speed up half your queries. FIND_VIDEO: search 'database index analyst tutorial' — recommended channel: EverSQL / Crunchy Data. Aim for 10 min or under.
Recap — Writing Index-Friendly Queries
Six index rules that change how you write SQL. Plus when to ask engineering for an index, and what to ask for.