Component family |
Big Data/File | |
Basic settings |
Property type |
Either Built-in or Repository Built-in: No property data stored centrally. Repository: Select the repository file in which the properties are stored. The fields that follow are completed automatically using the data retrieved. Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions. |
|
Use an existing connection |
Select this check box and in the Component List click the HDFS connection component from which you want to reuse the connection details already defined. Note that when a Job contains the parent Job and the child Job, Component List presents only the connection components in the same Job level. |
Version |
Distribution |
Select the cluster you are using from the drop-down list. The options in the list vary depending on the component you are using. Among these options, the following ones requires specific configuration:
In order to connect to a custom distribution, once selecting Custom, click the
|
Hadoop version |
Select the version of the Hadoop distribution you are using. The available options vary depending on the component you are using. Along with the evolution of Hadoop, please note the following changes:
| |
Authentication |
Use kerberos authentication |
If you are accessing the Hadoop cluster running with Kerberos security, select this check box, then, enter the Kerberos principal name for the NameNode in the field displayed. This enables you to use your user name to authenticate against the credentials stored in Kerberos.
This check box is available depending on the Hadoop distribution you are connecting to. |
Use a keytab to authenticate |
Select the Use a keytab to authenticate check box to log into a Kerberos-enabled Hadoop system using a given keytab file. A keytab file contains pairs of Kerberos principals and encrypted keys. You need to enter the principal to be used in the Principal field and the access path to the keytab file itself in the Keytab field. Note that the user that executes a keytab-enabled Job is not necessarily the one a principal designates but must have the right to read the keytab file being used. For example, the user name you are using to execute a Job is user1 and the principal to be used is guest; in this situation, ensure that user1 has the right to read the keytab file to be used. | |
|
NameNode URI |
Type in the URI of the Hadoop NameNode. The NameNode is the master node of a Hadoop system. For example, we assume that you have chosen a machine called masternode as the NameNode of an Apache Hadoop distribution, then the location is hdfs://masternode:portnumber. |
|
User name |
The User name field is available when you are not using Kerberos to authenticate. In the User name field, enter the login user name for your distribution. If you leave it empty, the user name of the machine hosting the Studio will be used. |
Group |
Enter the membership including the authentication user under which the HDFS instances were started. This field is available depending on the distribution you are using. | |
Schema and Edit schema |
A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository. Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions. The schema of this component is read-only. You can click Edit schema to view the schema. | |
File |
Browse to, or enter the path pointing to the data to be used in the file system. | |
|
Get file checksum |
Select this check box to generate and output the MD5 information of the file processed. Note that this is an HDFS only checksum and not a true MD5 hash that can be compared with the MD5 value obtained, for example, from tFileInputProperties, For further information about this component, see tFileInputProperties. |
Advanced settings |
Hadoop properties |
Talend Studio uses a default configuration for its engine to perform operations in a Hadoop distribution. If you need to use a custom configuration in a specific situation, complete this table with the property or properties to be customized. Then at runtime, the customized property or properties will override those default ones.
For further information about the properties required by Hadoop and its related systems such as HDFS and Hive, see the documentation of the Hadoop distribution you are using or see Apache's Hadoop documentation on http://hadoop.apache.org/docs and then select the version of the documentation you want. For demonstration purposes, the links to some properties are listed below:
|
tStatCatcher Statistics | Select this check box to gather the Job processing metadata at a Job level as well as at each component level. | |
Dynamic settings |
Click the [+] button to add a row in the table and fill the Code field with a context variable to choose your HDFS connection dynamically from multiple connections planned in your Job. This feature is useful when you need to access files in different HDFS systems or different distributions, especially when you are working in an environment where you cannot change your Job settings, for example, when your Job has to be deployed and executed independent of Talend Studio. The Dynamic settings table is available only when the Use an existing connection check box is selected in the Basic settings view. Once a dynamic parameter is defined, the Component List box in the Basic settings view becomes unusable. For examples on using dynamic parameters, see Scenario 3: Reading data from MySQL databases through context-based dynamic connections and Scenario: Reading data from different MySQL databases using dynamically loaded connection parameters. For more information on Dynamic settings and context variables, see Talend Studio User Guide. | |
Global Variables |
ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box. A Flow variable functions during the execution of a component while an After variable functions after the execution of the component. To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it. For further information about variables, see Talend Studio User Guide. | |
Usage |
tHDFSProperties can be standalone component or send the information it generates to its following component. | |
Prerequisites |
The Hadoop distribution must be properly installed, so as to guarantee the interaction with Talend Studio. The following list presents MapR related information for example.
For further information about how to install a Hadoop distribution, see the manuals corresponding to the Hadoop distribution you are using. | |
Log4j | If you are using a subscription-based version of the Studio, the activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide. For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html. | |
Limitation |
JRE 1.6+ is required. |