Why do queries sometimes take longer on smaller datasets?
Query operations are conducted on segments. indexes reduce the amount of time it takes to query a segment. If a segment has not been indexed, Milvus resorts to brute-force search on the raw data—drastically increasing query time.
Therefore, it usually takes longer to query on a small dataset (collection) because it has not built index. This is because the sizes of its segments have not reached the index-building threshold set by
create_index() to force Milvus to index segments that have reached the threshold but not yet been automatically indexed, significantly improving query performance.