All the nodes of PolarDB for PostgreSQL(Compatible with 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 PostgreSQL(Compatible with Oracle) provides nodes of the following specifications.

Table 1. Specifications of compute nodes
Node typeCPU and memoryMaximum storage capacityMaximum number of connections 1Internal bandwidthMaximum IOPSI/O bandwidth

2 cores

8 GB

5 TB8001 Gbps16,0001 Gbps

4 cores

16 GB

10 TB1,60010 Gbps64,0004 Gbps

8 cores

32 GB

10 TB3,20010 Gbps128,0008 Gbps

8 cores

64 GB

30 TB3,20010 Gbps160,00010 Gbps

16 cores

128 GB

50 TB12,80010 Gbps256,00016 Gbps

32 cores

256 GB

50 TB25,60010 Gbps384,00024 Gbps

64 cores

512 GB

100 TB36,00010 Gbps409,60024 Gbps

88 cores

710 GB

100 TB36,00025 Gbps512,00032 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 PostgreSQL(Compatible with 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.