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Updated on 2024-08-20 GMT+08:00
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Example: Parameters for Connecting to the Database in Different Scenarios

In the example, host:port represents a node, where host indicates the name or IP address of the server where the database resides, and port indicates the port number of the server where the database resides.

DR

A customer has two database clusters. Cluster A is the production cluster, and cluster B is the DR cluster. When the customer performs a DR failover, cluster A becomes the DR cluster, and cluster B becomes the production cluster. In this case, to avoid application restart or re-release caused by configuration file modification, the customer can write clusters A and B to the connection string when initializing the configuration file. In this case, if the primary cluster cannot be connected, the driver attempts to connect to the DR cluster. Assume that cluster A is {node1,node2,node3} and cluster B is {node4,node5,node6}.

Take the dual-cluster Dorado as an example. To connect to the new primary cluster only after the primary/standby switchover, you can set the URL as follows: 
jdbc:gaussdb://node1,node2,node3,node4,node5,node6/database

Load Balancing

A customer has a database cluster that contains the following nodes: {node1,node2,node3,node4,node5,node6,node7,node8,node9,node10,node11,node12}.

  1. The customer establishes 120 persistent connections in application A and expects that the connections on application A can be evenly distributed on each node in the current cluster. The URL can be configured as follows: 
    jdbc:gaussdb://node1,node2,node3/database?autoBalance=true
  2. The customer develops two applications B and C and wants the three applications to be evenly distributed on specified nodes. For example, the connections of application A are distributed on {node1,node2,node3,node4}. The connections of application B are distributed on {node5,node6,node7,node8}. The connections of application C are distributed on {node9,node10,node11,node12}. The URLs can be configured as follows (If the first four nodes in the URL cannot be connected, the application connects to the fifth node based on the information in the pgxc_node system catalog. All available nodes in the cluster are connected in polling mode.):

    Application A: jdbc:gaussdb://node1,node2,node3,node4,node5/database?autoBalance=priority4

    Application B: jdbc:gaussdb://node5,node6,node7,node8,node9/database?autoBalance=priority4

    Application C: jdbc:gaussdb://node9,node10,node11,node12,node1/database?autoBalance=priority4

  3. The customer develops more applications, uses the same connection configuration string, and expects that the application connections can be evenly distributed on each node in the cluster. The URL can be configured as follows: 
    jdbc:gaussdb://node1,node2,node3,node4/database?autoBalance=shuffle
  4. The customer has developed some applications and wants to establish connections in single-node session mode. The URL can be configured as follows: 
    jdbc:gaussdb://node1,node2,node3,node4/database?sessionType=singleNode&execTargetNode=your_dn_name
  5. If the customer does not want to use the load balancing function, configure the URL as follows: 
    jdbc:gaussdb://node1/database

    Or

    jdbc:gaussdb://node1/database?autoBalance=false

    When the autoBalance parameter is enabled, the interval for the JDBC to refresh the available CN list is 10s by default. You can use refreshCNIpListTime to set the interval:

    jdbc:gaussdb://node1,node2,node3,node4/database?autoBalance=true&refreshCNIpListTime=3

Log Diagnosis

If you encounter slow data import or some errors that are difficult to analyze, the trace log function can be enabled for diagnosis. The URL can be configured as follows:

jdbc:gaussdb://node1/database?loggerLevel=trace

High Performance

A customer may execute the same SQL statement for multiple times with different input parameters. To improve the execution efficiency, the prepareThreshold parameter can be enabled to avoid repeatedly generating execution plans. The URL can be configured as follows:

jdbc:gaussdb://node1/database?prepareThreshold=5

A customer queries 10 million data records at a time. To prevent memory overflow caused by simultaneous return of the data records, the defaultRowFetchSize parameter can be used. The URL can be configured as follows:

jdbc:gaussdb://node1/database?defaultRowFetchSize=50000

A customer needs to insert 10 million data records in batches. To improve efficiency, the batchMode parameter can be used. The URL can be configured as follows:

jdbc:gaussdb://node1/database?batchMode=on