javascript
db.users.createIndex({ email: 1 })Notes
Ideal for identity or lookup fields.
MongoDB Index Types and Query Patterns
Single-field, compound, multikey, text, wildcard, partial, TTL, and unique index patterns for MongoDB.
Export
Copy the compact sheet, download it, or print it.
Download
`D` dense toggle · `C` copy all
MongoDB index types
Match index type to the document shape and query shape.
javascript
db.orders.createIndex({ tenantId: 1, status: 1, createdAt: -1 })Notes
Column order still matters in MongoDB compound indexes.
Multikey index on an array field
Index documents that contain array values.
javascriptANYmongodbmultikeyarrays
javascript
db.products.createIndex({ tags: 1 })Notes
MongoDB automatically creates a multikey index when the indexed field contains arrays.
javascript
db.orders.createIndex(
{ createdAt: -1 },
{ partialFilterExpression: { shippedAt: { $exists: false } } }
)Notes
A strong way to shrink index size for hot subsets such as unshipped orders.
javascript
db.sessions.createIndex({ expiresAt: 1 }, { expireAfterSeconds: 0 })Notes
Useful for sessions, caches, temporary tokens, and ephemeral telemetry.
javascript
db.events.createIndex({ "$**": 1 })Notes
Wildcard indexes can help when documents contain highly variable keys, though they should be used carefully.
Verify with explain
Measure whether an index reduced keys and docs examined.
Explain a query with execution stats
Inspect planner and runtime behavior.
javascriptANYmongodbexplainexecutionStats
javascript
db.orders.find({ tenantId: 7, status: "paid" }).sort({ createdAt: -1 }).explain("executionStats")Notes
Check keys examined, docs examined, winning plan, and whether the compound index is actually used.
More in Database Indexing
Indexing Anti-Patterns and Maintenance
Avoid over-indexing, duplicate indexes, low-value indexes, stale statistics, and maintenance mistakes.
EXPLAIN, ANALYZE, and Verify Index Usage
Use EXPLAIN tools across PostgreSQL, MySQL, SQLite, and MongoDB to prove whether an index actually helps.
Partial, Expression, and Functional Indexes
High-leverage index patterns for subsets of data and computed predicates across PostgreSQL, MySQL, and SQLite.
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.