sqlANYpostgresqlexplainanalyze
sql
EXPLAIN (ANALYZE, BUFFERS) SELECT * FROM users WHERE email = 'a@example.com';This is often the first stop for PostgreSQL tuning.
EXPLAIN, ANALYZE, and Verify Index Usage
Use EXPLAIN tools across PostgreSQL, MySQL, SQLite, and MongoDB to prove whether an index actually helps.
Export
Copy the compact sheet, download it, or print it.
Download
`D` dense toggle · `C` copy all
Cross-database tools
Different engines use different plan inspection commands.
sqlANYmysqlexplain
sql
EXPLAIN SELECT * FROM users WHERE email = 'a@example.com';Check the selected key, rows estimate, and extras such as filesort or temporary operations.
sqlANYsqliteexplain-query-plan
sql
EXPLAIN QUERY PLAN SELECT * FROM users WHERE email = 'a@example.com';Very useful in mobile, local, and embedded app debugging.
javascriptANYmongodbexplain
javascript
db.users.find({ email: 'a@example.com' }).explain('executionStats')A large drop in docs examined is a strong sign the index is paying off.
What good looks like
General signals that the index is helping.
textANYchecklistverification
text
Look for:
- indexed search instead of full scan
- fewer rows/docs examined
- fewer extra sorts
- lower latency under realistic load
- acceptable write overheadDo not stop at 'the index exists'. Confirm that it materially improves the real workload.
More in Database Indexing
Indexing Anti-Patterns and Maintenance
Avoid over-indexing, duplicate indexes, low-value indexes, stale statistics, and maintenance mistakes.
Partial, Expression, and Functional Indexes
High-leverage index patterns for subsets of data and computed predicates across PostgreSQL, MySQL, and SQLite.
MongoDB Index Types and Query Patterns
Single-field, compound, multikey, text, wildcard, partial, TTL, and unique index patterns for MongoDB.
SQLite Indexes and Query Planner
SQLite CREATE INDEX patterns, expression and partial indexes, EXPLAIN QUERY PLAN, and lightweight performance tuning.
MySQL Index Strategies and Verification
Composite indexes, invisible indexes, descending indexes, generated-column indexing, and EXPLAIN workflows in MySQL.
PostgreSQL Index Types and Strategies
Use PostgreSQL B-tree, GIN, GiST, BRIN, partial indexes, expression indexes, and concurrent builds effectively.