private static Database getDatabaseType(ConfigManager configManager, String datasourceName) {
        ConfigReader configReader = configManager.generateConfigReader("wso2.datasources", datasourceName);
        String databaseType = configReader.readConfig("driverClassName", "null").toLowerCase();
        if (databaseType.contains("mysql")) {
            return Database.MYSQL;
        } else if (databaseType.contains("oracle")) {
            return Database.ORACLE;
        } else if (databaseType.contains("mssql") || databaseType.contains("sqlserver")) {
            return Database.MSSQL;
        } else if (databaseType.contains("postgres")) {
            return Database.PostgreSQL;
        } else {
            log.warn("Provided database type " + databaseType + "is not recognized as a supported database type for" +
                    " persisted incremental aggregation, using MySQL as default ");
            return Database.MYSQL;
        }
    }
This is the parser class of incremental aggregation definition.
modules/siddhi-core/src/main/java/io/siddhi/core/util/parser/AggregationParser.java