Search Enhancement Features for OpenSearch Clusters

Compared with open-source OpenSearch, OpenSearch clusters in CSS have many enhanced features. Table 1 lists these enhanced features and the corresponding cluster versions.

**Table 1** Search enhancement features for OpenSearch clusters
Enhanced Feature	Description	Cluster Version	Details
Vector search	Unstructured data, such as images, videos, and language corpora, is converted into vectors, which are searched based on similarity using either an exact or approximate nearest neighbors algorithm.	OpenSearch 1.3.6, OpenSearch 2.19.0	About CSS Vector Search
Storage-compute decoupling	CSS stores new data as hot data on SSDs to ensure optimal query performance, and historical data as cold data in OBS to cut storage costs. Compared with cold/hot storage switchover, storage-compute decoupling is a better option for use cases that are not particularly demanding in terms of search performance, as cold data is stored in OBS, which cuts storage costs.	OpenSearch 1.3.6, OpenSearch 2.19.0	Configuring Decoupled Storage and Compute for an OpenSearch Cluster
Flow control	Protects clusters from overload through flow control policies, such as client request throttling, shard indexing backpressure, and traffic pattern analysis, ensuring proper resource allocation and risk prevention.	OpenSearch 2.19.0	Configuring Flow Control for an OpenSearch Cluster
Large query isolation	Helps effectively manage memory-intensive, time-consuming query requests, ensuring cluster stability.	OpenSearch 2.19.0	Configuring Large Query Isolation for an OpenSearch Cluster
Enhanced aggregation	CSS OpenSearch clusters enhance aggregation performance in the face of large data volumes by leveraging vectorization and optimized clustering, enabling faster analytics and decision-making in complex situations.	OpenSearch 2.19.0	Configuring Enhanced Aggregation for an OpenSearch Cluster
Read/write splitting	Read/write splitting directs writes to the leader cluster and queries to the follower cluster, separating the loads. If the leader becomes unavailable, the follower automatically upgrades to leader to ensure service continuity. You may use this feature where high availability and high query performance are prioritized.	OpenSearch 2.19.0	Configuring Read/Write Splitting Between Two OpenSearch Clusters
Switchover between hot and cold storage	You can keep hot data on high-performance servers to ensure fast query response times (in seconds). For historical data that requires a query response time of minutes, you can keep it on large-capacity, low-specs servers as cold data. This allows you to cut storage costs and improve search efficiency. Compared with storage-compute decoupling, cold/hot storage switchover is a better option for use cases that are demanding in terms of search performance. Cold data is stored on local cold data nodes in the cluster. The storage capacity available depends on the number of cold data nodes and their disk capacity. The storage cost is higher than that of OBS.	This feature is supported as long as the cluster has cold data nodes.	Switching Between Hot and Cold Storage for an OpenSearch Cluster
Index recycle bin	To prevent data loss caused by accidental deletion, CSS provides an index recycle bin. When enabled, deleted indexes are temporarily stored in the recycle bin, allowing for recovery before they are permanently removed. This feature improves data reliability and operational security.	OpenSearch 2.19.0	Configuring an Index Recycle Bin for an OpenSearch Cluster