Question

You manage a write-heavy Azure Cosmos DB for NoSQL container that ingests millions of IoT event documents per hour. Each document has 40+ properties, but analysts only ever filter on three known properties: deviceId, eventType, and timestamp. Ingestion RU charges are unexpectedly high, and profiling shows a large portion of write RUs is spent maintaining the index. Which indexing policy change will most effectively reduce write RU cost while preserving query performance for the analysts' known filters?

Accepted Answer

Set includedPaths to only the three filtered property paths and add '/*' to excludedPaths.

Answer

Set the indexing mode to 'none' so no properties are indexed during writes.

Answer

Change the includedPaths to '/*' (wildcard) and rely on the default automatic indexing.

Answer

Add a composite index across all 40 properties to consolidate index maintenance.