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Database Dialects

What are database dialects?

The AWS Advanced JDBC Driver is a wrapper that requires an underlying driver, and it is meant to be compatible with any JDBC driver. Database dialects help the AWS JDBC Driver determine what kind of underlying database is being used. To function correctly, the AWS JDBC Driver requires details unique to specific databases such as the default port number or the method to get the current host from the database. These details can be defined and provided to the AWS JDBC Driver by using database dialects.

Configuration Parameters

Name Required Description Example
wrapperDialect No (see notes below) The dialect code of the desired database type. DialectCodes.AURORA_MYSQL or aurora-mysql

NOTES:

The wrapperDialect parameter is not required. When it is not provided by the user, the AWS JDBC Driver will attempt to determine which of the existing dialects to use based on other connection details. However, if the dialect is known by the user, it is preferable to set the wrapperDialect parameter because it will take time to resolve the dialect.

List of Available Dialect Codes

Dialect codes specify what kind of database any connections will be made to.

Dialect Code Reference Value Database
AURORA_MYSQL aurora-mysql Aurora MySQL
RDS_MYSQL rds-mysql Amazon RDS MySQL
MYSQL mysql MySQL
AURORA_PG aurora-pg Aurora PostgreSQL
RDS_PG rds-pg Amazon RDS PostgreSQL
PG pg PostgreSQL
MARIADB mariadb MariaDB
CUSTOM custom See custom dialects. This code is not required when using custom dialects.
UNKNOWN unknown Unknown. Although this code is available, do not use it as it will result in errors.

Custom Dialects

If you are interested in using the AWS JDBC Driver but your desired database type is not currently supported, it is possible to create a custom dialect.

To create a custom dialect, implement the Dialect interface. For databases clusters that are aware of their topology, the TopologyAwareDatabaseCluster interface should also be implemented. See the following classes for examples:

  • PgDialect
    • This is a generic dialect that should work with any PostgreSQL database.
  • AuroraPgDialect
    • This dialect is an extension of PgDialect, but also implements the TopologyAwareDatabaseCluster interface.

Once the custom dialect class has been created, tell the AWS JDBC Driver to use it with the setCustomDialect method in the DialectManager class. It is not necessary to set the wrawpperDialect parameter. See below for an example:

Dialect myDialect = new CustomDialect();
DialectManager.setCustomDialect(myDialect);