tHCatalogLoad Standard properties

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.

Distribution

1. Select Import from existing version to import an officially supported distribution as base and then add other required jar files which the base distribution does not provide.

2. Select Import from zip to import the configuration zip for the custom distribution to be used. This zip file should contain the libraries of the different Hadoop elements and the index file of these libraries.

   Note that custom versions are not officially supported by Talend . Talend and its community provide you with the opportunity to connect to custom versions from Talend Studio but cannot guarantee that the configuration of whichever version you choose will be easy, due to the wide range of different Hadoop distributions and versions that are available. As such, you should only attempt to set up such a connection if you have sufficient Hadoop experience to handle any issues on your own.

   Information noteNote:

   In this dialog box, the active check box must be kept selected so as to import the jar files pertinent to the connection to be created between the custom distribution and this component.

   For a step-by-step example about how to connect to a custom distribution and share this connection, see Hortonworks.

HCatalog version

Select the version of the Hadoop distribution you are using. The available options vary depending on the component you are using.

Templeton hostname

Fill this field with the URL of Templeton Webservice.

Templeton port

Fill this field with the port of URL of Templeton Webservice. By default, this value is 50111.

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 username to authenticate against the credentials stored in Kerberos.

This check box is available depending on the Hadoop distribution you are connecting to.

Select the Use a keytab to authenticate check box to log into a Kerberos-enabled 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. This keytab file must be stored in the machine in which your Job actually runs, for example, on a Talend JobServer.

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 username 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.

Database

Enter the name of the database you need to write data in. This database must already exist.

Table

Enter the name of the table you need to write data in. This table must already exist.

Partition

Fill this field to specify one or more partitions for the partition operation on the specified table. When you specify multiple partitions, use commas to separate every two partitions and use double quotation marks to quote the partition string.

If you are reading a non-partitioned table, leave this field empty.

Fill this field with the username for the DB authentication.

Enter the absolute path pointing to the HDFS location from which data is read.

Die on error

This check box is cleared by default, meaning to skip the row on error and to complete the process for error-free rows.

Fill this field with the path to which log files are stored.

Error Output Folder

tStatCatcher Statistics

Select this check box to gather the Job processing metadata at the Job level as well as at each component level.

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 more information about variables, see Using contexts and variables.

Usage rule

This component can be used in a single-component subJob.

HCatalog is built on top of the Hive metastore to provide read and write interface for Pig and MapReduce, so that the latter systems can use the metadata of Hive to easily read and write data in HDFS.

For further information, see Apache documentation about HCatalog: https://cwiki.apache.org/confluence/display/Hive/HCatalog.

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.

• Ensure that you have installed the MapR client in the machine where Talend Studio is, and added the MapR client library to the PATH variable of that machine. According to MapR's documentation, the library or libraries of a MapR client corresponding to each OS version can be found under MAPR_INSTALL\ hadoop\hadoop-VERSION\lib\native. For example, the library for Windows is \lib\native\MapRClient.dll in the MapR client jar file.

  Without adding the specified library or libraries, you may encounter the following error: no MapRClient in java.library.path.

• Set the -Djava.library.path argument, for example, in the Job Run VM arguments area of the Run/Debug view in the Preferences dialog box in the Window menu. This argument provides to Talend Studio the path to the native library of that MapR client. This allows the subscription-based users to make full use of the Data viewer to view locally in Talend Studio the data stored in MapR.

For further information about how to install a Hadoop distribution, see the manuals corresponding to the Hadoop distribution you are using.

Limitation

When Use kerberos authentication is selected, the component cannot work with IBM JVM.