All the nodes of PolarDB for Oracle are dedicated nodes. The CPU, memory, storage, and I/O resources allocated to dedicated nodes are not shared by other nodes. Therefore, the performance of dedicated nodes is more stable and reliable.

PolarDB for Oracle provides nodes of the following specifications.

Table 1. Specifications of compute nodes
Node type CPU and memory Maximum storage capacity Maximum number of connections 1 Internal bandwidth Maximum IOPS I/O bandwidth
polar.o.x4.medium

2 cores

8 GB

5 TB 800 1 Gbps 16,000 1 Gbps
polar.o.x4.large

4 cores

16 GB

10 TB 1,600 10 Gbps 64,000 4 Gbps
polar.o.x4.xlarge

8 cores

32 GB

10 TB 3,200 10 Gbps 128,000 8 Gbps
polar.o.x8.xlarge

8 cores

64 GB

30 TB 3,200 10 Gbps 160,000 10 Gbps
polar.o.x8.2xlarge

16 cores

128 GB

50 TB 12,800 10 Gbps 256,000 16 Gbps
polar.o.x8.4xlarge

32 cores

256 GB

50 TB 25,600 10 Gbps 384,000 24 Gbps
polar.o.x8.8xlarge

64 cores

512 GB

100 TB 36,000 10 Gbps 409,600 24 Gbps
polar.o.x8.12xlarge

88 cores

710 GB

100 TB 36,000 25 Gbps 512,000 32 Gbps
Note Maximum number of connections 1: the limit on the number of connections, which is indicated by the value of the max_connections parameter. The actual number of connections supported by a compute node may vary based on your business. For more information, see Maximum number of connections.

Maximum number of connections

  • If the number of concurrent connections in your PolarDB for Oracle cluster exceeds the maximum number, new connections cannot be established, or existing connections will time out.

    The amount of memory consumed by each connection varies in different business systems. As a result, the actual number of connections supported by your PolarDB cluster may be different from the maximum number in the specifications.

  • Query the maximum number of connections under the current system configurations.
    show max_connections;
  • Query the current number of connections.
    select count(1) from pg_stat_activity;
  • We recommend that you monitor the status of your cluster and make sure that the number of connections does not exceed the recommended value. You can calculate the recommended value based on following formula:

    LEAST({DBInstanceClassMemory/11MB}, 5000)

  • If your application requires a larger number of connections than the maximum number, you must use a PolarDB cluster with larger memory.