Composite index
A composite index is a database index whose key contains multiple fields or columns, ordered according to the index definition.
Just Use Postgres!
A composite index is a database index defined over multiple columns, ordering entries first by one column and then by subsequent columns.
- How it is used
- Optimizes queries that filter or order by related columns, such as regional leaderboards and device-specific time-series ranges.
- How deep it goes
- Explains column ordering, leading-column behavior, execution plans, and caveats, but defers broader index administration.
- Examples
- Demonstrates regional player rankings, filtered score queries, and smartwatch measurements filtered by timestamp and device.
- What you can do after
- Diagnose/debug with it by creating indexes, reading EXPLAIN plans, and checking whether ordering and filters use the intended index.
MongoDB 8.0 in Action, Third Edition
A compound index is an index whose key consists of multiple document fields.
- How it is used
- Speeds recurring MongoDB queries that filter on multiple fields or sort on multiple fields.
- How deep it goes
- Defines index prefixes, works through creation commands and execution plans, and specifies sort-key order without detailing index storage internals.
- Examples
- Uses movie indexes on release year, type, IMDb rating, and title, plus theater and runtime sorting queries.
- What you can do after
- Build it from scratch with createIndex, align field order with queries and sorts, and check index use with explain("executionStats").
Read how MongoDB 8.0 in Action, Third Edition explains composite index →
Natural Language Processing in Action, Second Edition
A composite index combines multiple indexing algorithms or stages into a single retrieval structure.
- How it is used
- Uses staged vector retrieval to reduce memory pressure while supporting large-scale nearest-neighbor search.
- How deep it goes
- Defines multi-stage indexing and explains memory and configuration tradeoffs, but stops short of implementation procedures or tuning recipes.
- Examples
- Uses IVFPQ, HNSW plus PQ, NumPy quantization, Faiss, Weaviate, and a New York Times ANN comparison.
- What you can do after
- Evaluate composite-index tradeoffs and recognize when memory savings justify added configuration complexity.
Read how Natural Language Processing in Action, Second Edition explains composite index →
Related concepts
- indexingkind of · Indexing is the organization or use of positions, keys, or lookup structures to identify and retrieve selected data or elements.
- single-column indexcontrasts with · A single-column index is a database index whose key is derived from one field or column and whose entries are organized by its values.
- sorting algorithmused by · A sorting algorithm is a procedure that rearranges elements of a collection into an order determined by an ordering criterion.
- ESR ruleconfigured by · The ESR rule is a MongoDB compound-index design guideline that orders equality fields before sort fields and range fields.
- bitmap index scanuses · A bitmap index scan is a query-plan operation that uses an index to build a bitmap of matching row locations before retrieving the corresponding table rows.
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