javascriptANYmongodbsingle-field
javascript
db.users.createIndex({ email: 1 })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.
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Copy the compact sheet, download it, or print it.
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MongoDB index types
Match index type to the document shape and query shape.
javascriptANYmongodbcompound
javascript
db.orders.createIndex({ tenantId: 1, status: 1, createdAt: -1 })Column order still matters in MongoDB compound indexes.
javascriptANYmongodbmultikeyarrays
javascript
db.products.createIndex({ tags: 1 })MongoDB automatically creates a multikey index when the indexed field contains arrays.
javascriptANYmongodbpartial-index
javascript
db.orders.createIndex(
{ createdAt: -1 },
{ partialFilterExpression: { shippedAt: { $exists: false } } }
)A strong way to shrink index size for hot subsets such as unshipped orders.
javascriptANYmongodbttl
javascript
db.sessions.createIndex({ expiresAt: 1 }, { expireAfterSeconds: 0 })Useful for sessions, caches, temporary tokens, and ephemeral telemetry.
javascriptANYmongodbwildcard
javascript
db.events.createIndex({ "$**": 1 })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.
javascriptANYmongodbexplainexecutionStats
javascript
db.orders.find({ tenantId: 7, status: "paid" }).sort({ createdAt: -1 }).explain("executionStats")Check keys examined, docs examined, winning plan, and whether the compound index is actually used.
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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
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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.