Help Center/ GaussDB/ Developer Guide(Distributed_V2.0-3.x)/ Application Development Guide/ Development Based on ODBC/ Typical Application Development Examples/ Typical Application Scenarios and Configurations
Updated on 2025-03-13 GMT+08:00
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Typical Application Scenarios and Configurations

Log Diagnosis

ODBC logs are classified into unixODBC driver manager logs and psqlODBC driver logs. The former is used to trace whether the application API is successfully executed, and the latter is used to locate problems based on DFX logs generated during underlying implementation.

The unixODBC log needs to be configured in the odbcinst.ini file: 
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[ODBC]
Trace=Yes
TraceFile=/path/to/odbctrace.log

[GaussMPP]
Driver64=/usr/local/lib/psqlodbcw.so
setup=/usr/local/lib/psqlodbcw.so
For psqlODBC logs, you only need to add the following content to odbc.ini: 
[gaussdb]
Driver=GaussMPP
Servername=10.10.0.13 # Database server IP address
...
Debug=1 # Enable the debug log function of the driver.

The unixODBC logs are generated in the path configured by TraceFile. The psqlODBC generates the mylog_xxx.log file in the /tmp/ directory.

Load Balancing

Load balancing can be enabled when there are a large number of concurrent applications.
  • Load balancing is to randomly distribute concurrent connections to all CNs to prevent a single CN from being overloaded and improve performance.
  • Set AutoBalance to 1 to enable load balancing.
  • Set RefreshCNListTime to 5 as required. The default refresh interval is 10s.
  • Set Priority to 1 as required. In this case, concurrent connections are preferentially sent to the CNs configured in the configuration file. If all the configured CNs are unavailable, the connections are distributed to the remaining CNs.

Example:

Six CNs, namely, CN1, CN2, CN3, CN4, CN5, and CN6, are configured in the cluster, and four CNs, namely, CN1, CN2, CN3, and CN4, are configured in the configuration file.

Example content of the odbc.ini file:

[gaussdb]
Driver=GaussMPP
Servername=10.145.130.26,10.145.130.27,10.145.130.28,10.145.130.29  # IP address of the database server.
Database=postgres  # Database name.
Username=omm  # Database username.
Password=  # Database user password.
Port=8000  # Database listening port.
Sslmode=allow
AutoBalance=1
RefreshCNListTime=3
Priority=1

If the configuration file and cluster environment are the same as those in the example, concurrent connections are randomly and evenly distributed to CN1, CN2, CN3, and CN4. When CN1, CN2, CN3, and CN4 are all unavailable, concurrent connections are randomly and evenly sent to CN5 and CN6. If any CN among CN1, CN2, CN3, and CN4 becomes available, the connections are not sent to CN5 and CN6 but to the available CN.