SQL guides
Learn how to read query plans and choose indexes with worked SQLite examples. Compare the returned rows and database work before and after each change.
Start with the tuning workflow, then read the guides on plans and indexes.
1. 3 minute read
A repeatable way to tune SQL queries
Use a repeatable workflow to check results, read a plan, and verify an improvement.
2. 3 minute read
How to read a query execution plan
Recognize scans, searches, and sorts in a SQLite query plan.
3. 3 minute read
How SQL indexes reduce query work
Choose index columns based on the query and the share of rows its filter matches.
4. 3 minute read
What a covering index does
See when an index can answer a query without visiting the table.
5. 3 minute read
How to use SQLite EXPLAIN QUERY PLAN
Connect EXPLAIN QUERY PLAN output to the work a query asks SQLite to do.
6. 5 minute read
What the N+1 query problem is and how to fix it
Spot repeated application queries and compare them with a joined query.
Keep learning
Worked SQL examples walk through source rows, queries, and results.
How to use QueryPlan explains Run, Submit, hints, and saved progress.