How does using bulk indexing requests impact the overall indexing rate compared to single document indexing?

Using bulk indexing requests significantly improves the overall indexing rate compared to sending individual document indexing requests. Each request to Elasticsearch incurs network latency, TCP overhead, and processing costs on both the client and server side. By batching multiple documents into a single bulk request, these overheads are amortized over many documents. This reduces the number of network round trips, allows Elasticsearch to optimize internal write operations (e.g., merging segments more efficiently), and makes better use of I/O resources. A well-tuned bulk request size can lead to an order of magnitude (or more) increase in indexing throughput compared to single-document indexing.