You're viewing version 2.12 of the OpenSearch documentation. This version is no longer maintained. For the latest version, see the current documentation. For information about OpenSearch version maintenance, see Release Schedule and Maintenance Policy.

k-NN settings

The k-NN plugin adds several new cluster settings. To learn more about static and dynamic settings, see Configuring OpenSearch.

Cluster settings

Setting	Default	Description
`knn.algo_param.index_thread_qty`	1	The number of threads used for native library index creation. Keeping this value low reduces the CPU impact of the k-NN plugin, but also reduces indexing performance.
`knn.cache.item.expiry.enabled`	false	Whether to remove native library indexes that have not been accessed for a certain duration from memory.
`knn.cache.item.expiry.minutes`	3h	If enabled, the idle time before removing a native library index from memory.
`knn.circuit_breaker.unset.percentage`	75%	The native memory usage threshold for the circuit breaker. Memory usage must be below this percentage of `knn.memory.circuit_breaker.limit` for `knn.circuit_breaker.triggered` to remain false.
`knn.circuit_breaker.triggered`	false	True when memory usage exceeds the `knn.circuit_breaker.unset.percentage` value.
`knn.memory.circuit_breaker.limit`	50%	The native memory limit for native library indexes. At the default value, if a machine has 100 GB of memory and the JVM uses 32 GB, the k-NN plugin uses 50% of the remaining 68 GB (34 GB). If memory usage exceeds this value, k-NN removes the least recently used native library indexes.
`knn.memory.circuit_breaker.enabled`	true	Whether to enable the k-NN memory circuit breaker.
`knn.plugin.enabled`	true	Enables or disables the k-NN plugin.
`knn.model.index.number_of_shards`	1	The number of shards to use for the model system index, the OpenSearch index that stores the models used for Approximate Nearest Neighbor (ANN) search.
`knn.model.index.number_of_replicas`	1	The number of replica shards to use for the model system index. Generally, in a multi-node cluster, this should be at least 1 to increase stability.
`knn.advanced.filtered_exact_search_threshold`	null	The threshold value for the filtered IDs that is used to switch to exact search during filtered ANN search. If the number of filtered IDs in a segment is less than this setting’s value, exact search will be performed on the filtered IDs.