Vertica is a column-oriented database that uses the massively parallel processing (MPP) architecture. Vertica Reader reads data from Vertica. This topic describes how Vertica Reader works, the parameters that are supported by Vertica Reader, and how to configure Vertica Reader by using the codeless user interface (UI) and code editor.

Notice Vertica Reader supports only exclusive resource groups for Data Integration, but not the shared resource group or custom resource groups for Data Integration. For more information, see Create and use an exclusive resource group for Data Integration and Create a custom resource group for Data Integration.

How it works

Vertica Reader connects to a remote Vertica database by using Java Database Connectivity (JDBC), generates an SQL statement based on your configurations, and then sends the statement to the database. The system executes the statement on the database and returns data. Then, Vertica Reader assembles the returned data into abstract datasets of the data types supported by Data Integration and sends the datasets to a writer.
  • Vertica Reader generates the SQL statement based on the settings of the table, column, and where parameters and sends the generated statement to the Vertica database.
  • If you specify the querySql parameter, Vertica Reader directly sends the value of this parameter to the Vertica database.

Vertica Reader connects to a Vertica database by using the Vertica JDBC driver. You must make sure that the driver version is compatible with your Vertica database. Vertica Reader uses the Vertica JDBC driver of the following version: 

<dependency>
    <groupId>com.vertica</groupId>
    <artifactId>vertica-jdbc</artifactId>
    <version>7.1.2</version>
</dependency>

Parameters

Parameter Description Required Default value
datasource The name of the data source. It must be the same as the name of the added data source. You can add data sources by using the code editor. Yes No default value
jdbcUrl The JDBC URL that is used to connect to the Vertica database. You can specify multiple JDBC URLs for a database. Specify JDBC URLs in a JSON array.

If you specify multiple JDBC URLs, Vertica Reader verifies the connectivity of the URLs in sequence to find a valid URL. If no URL is valid, Vertica Reader returns an error.

Note The jdbcUrl parameter must be included in the connection parameter.

The value of the jdbcUrl parameter must comply with the standard format that is supported by Vertica. You can also specify the information of the attachment facility. Example: jdbc:vertica://1**.0.0.1:3306/database.

No No default value
username The username that is used to connect to the database. No No default value
password The password that is used to connect to the database. No No default value
table The name of the table from which you want to read data. Vertica Reader can read data from multiple tables. Specify the table names in a JSON array.

If you specify multiple tables, make sure that the tables have the same schema. Vertica Reader does not check whether the tables have the same schema.

Note The table parameter must be included in the connection parameter.
Yes No default value
column The names of the columns from which you want to read data. Specify the names in a JSON array. The default value is [ * ], which indicates all the columns in the source table.
  • You can select specific columns to read.
  • The column order can be changed. This indicates that you can specify columns in an order different from the order specified by the schema of the source table.
  • Constants are supported.
  • The column parameter must explicitly specify all the columns from which you want to read data. The parameter cannot be left empty.
Yes No default value
splitPk The field that is used for data sharding when Vertica Reader reads data. If you specify this parameter, the source table is sharded based on the value of this parameter. Data Integration then runs parallel threads to read data. This improves data synchronization efficiency.
  • We recommend that you set the splitPk parameter to the name of the primary key column of the table. Data can be evenly distributed to different shards based on the primary key column, instead of being intensively distributed only to specific shards.
  • The splitPk parameter supports sharding only for data of integer data types. If you set this parameter to a field of an unsupported data type, such as a string, floating point, or date data type, Vertica Reader returns an error.
  • If the splitPk parameter is left empty, Vertica Reader uses a single thread to read data from the source table.
No No default value
where The WHERE clause. Vertica Reader generates an SQL statement based on the settings of the table, column, and where parameters and uses the generated statement to read data.

For example, when you perform a test, you can specify the where parameter to filter data. In actual business scenarios, you can set the where parameter to gmt_create > $bizdate to read the data that is generated on the current day.

  • You can use the WHERE clause to read incremental data.
  • If the where parameter is not provided or is left empty, Vertica Reader reads all data.
No No default value
querySql The SQL statement that is used for refined data filtering. If you specify this parameter, Data Integration filters data based only on the value of this parameter.

If you specify the querySql parameter, Vertica Reader ignores the settings of the table, column, and where parameters.

No No default value
fetchSize The number of data records to read at a time. This parameter determines the number of interactions between Data Integration and Vertica and affects read efficiency.
Note If you set this parameter to a value greater than 2048, an out of memory (OOM) error may occur during data synchronization.
No 1,024

Configure Vertica Reader by using the codeless UI

This method is not supported.

Configure Vertica Reader by using the code editor

In the following code, a synchronization node is configured to read data from Vertica. For more information about how to configure a synchronization node by using the code editor, see Create a sync node by using the code editor. 
{
    "type": "job",
    "steps": [
        {
            "stepType": "vertica", // The reader type. 
            "parameter": {
                "datasource": "", // The name of the data source. 
                "username": "",
                "password": "",
                "where": "",
                "column": [ // The names of the columns from which you want to read data. 
                    "id",
                    "name"
                ],
                "splitPk": "id",
                "connection": [
                    {
                        "table": [ // The name of the table from which you want to read data. 
                            "table"
                        ],
                        "jdbcUrl": [
                            "jdbc:vertica://host:port/database"
                        ]
                    }
                ]
            },
            "name": "Reader",
            "category": "reader"
        },
        {
            "stepType": "stream",
            "parameter": {
                "print": false,
                "fieldDelimiter": ","
            },
            "name": "Writer",
            "category": "writer"
        }
    ],
    "version": "2.0",
    "order": {
        "hops": [
            {
                "from": "Reader",
                "to": "Writer"
            }
        ]
    },
    "setting": {
        "errorLimit": {
            "record": "0" // The maximum number of dirty data records allowed. 
        },
        "speed": {
            "throttle": true, // Specifies whether to enable bandwidth throttling. The value false indicates that bandwidth throttling is disabled, and the value true indicates that bandwidth throttling is enabled. The mbps parameter takes effect only when the throttle parameter is set to true. 
            "concurrent": 1, // The maximum number of parallel threads. 
                        "mbps":"12"// The maximum transmission rate.
        }
    }
}