Use this checklist before creating a new index.

Section: Quick checklist

Index decision checklist

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1. Is the query slow enough to matter?
2. Is the pattern common in production?
3. Is the filter selective?
4. Can one composite index cover multiple common queries?
5. Does EXPLAIN show scans or expensive sorts?
6. What write and storage cost will this add?
Explanation

Good indexing starts with workload evidence rather than intuition alone.

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Same sheet · prioritizing Quick checklist
Measure with EXPLAIN before and after
Validate improvement instead of guessing.
OpenIn sheetsqlsame section
What an index does
Indexes trade storage and write cost for faster reads.
Prefer high-selectivity columns
Columns with many distinct values tend to benefit more.
Remember the write cost
Every extra index must be maintained during inserts, updates, and deletes.
Composite index left-prefix rule
Use column order that matches real filter patterns.
Index joins and sorts too
Indexing is not just for filters.