ApsaraDB for MongoDB - Pay-as-you-go Sharded Cluster Instances Support Read-only Nodes
Target customers: large and medium-sized enterprise users. Features released: Each shard in an ApsaraDB MongoDB sharded cluster instance uses a three-node architecture. Only the primary and secondary nodes process read requests. Data skew or hotspot data reads may cause performance bottlenecks. The previous practice is to upgrade shard specifications or add more shards to expand storage capacity or read/write parallel processing capabilities. The former method causes transient shard connections, while the latter method causes sharp increase in costs. ApsaraDB for MongoDB sharded cluster instances that use the subscription billing method now support read-only nodes to relieve the read operation pressure on primary and secondary nodes. When you create an instance, you can create up to five read-only nodes for all shard nodes. When the instance is running, you can add or delete read-only nodes for existing shard nodes or create up to five read-only nodes when you add a shard node. This feature is launched in all regions and zones that support ApsaraDB for MongoDB sharded cluster instances and available for the instances that run MongoDB 3.4, 4.0, and 4.2.