tPigLoad Properties - 6.3

Component family

Big Data / Hadoop

Basic settings

Property type

Either Built-In or Repository.

Built-In: No property data stored centrally.

Repository: Select the repository file where the properties are stored.

The properties are stored centrally under the Hadoop Cluster node of the Repository tree.

The fields that come after are pre-filled in using the fetched data.

For further information about the Hadoop Cluster node, see the Getting Started Guide.

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.

Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available:

Built-In: You create and store the schema locally for this component only. Related topic: see Talend Studio User Guide.

Repository: You have already created the schema and stored it in the Repository. You can reuse it in various projects and Job designs. Related topic: see Talend Studio User Guide.

Local

Click this radio button to run Pig scripts in Local mode. In this mode, all files are installed and run from your local host and file system.

Tez

Click this radio button to run the Pig Job on the Tez framework.

This Tez mode is available only when you are using one of the following distributions:

Before using Tez, ensure that the Hadoop cluster you are using supports Tez. You will need to configure the access to the relevant Tez libraries via the Advanced settings view of this component.

For further information about Pig on Tez, see Apache's related documentation in https://cwiki.apache.org/confluence/display/PIG/Pig+on+Tez.

Map/Reduce

Click this radio button to run Pig scripts in Map/Reduce mode.

Once selecting this mode, you need to complete the fields in the Configuration area that appears:

WebHCat configuration

Enter the address and the authentication information of the WebHCat service of the Microsoft HD Insight cluster to be used. The Studio uses this service to submit the Job to the HD Insight cluster.

In the Job result folder field, enter the location in which you want to store the execution result of a Job in the Azure Storage to be used.

HDInsight configuration

Enter the authentication information of the HD Insight cluster to be used.

Windows Azure Storage configuration

Enter the address and the authentication information of the Azure Storage account to be used.

In the Container field, enter the name of the container to be used.

In the Deployment Blob field, enter the location in which you want to store the current Job and its dependent libraries in this Azure Storage account.

Inspect the classpath for configurations

Select this check box to allow the component to check the configuration files in the directory you have set with the $HADOOP_CONF_DIR variable and directly read parameters from these files in this directory. This feature allows you to easily change the Hadoop configuration for the component to switch between different environments, for example, from a test environment to a production environment.

In this situation, the fields or options used to configure Hadoop connection and/or Kerberos security are hidden.

If you want to use certain parameters such as the Kerberos parameters but these parameters are not included in these Hadoop configuration files, you need to create a file called talend-site.xml and put this file into the same directory defined with $HADOOP_CONF_DIR. This talend-site.xml file should read as follows:

<!-- Put site-specific property overrides in this file. --> 
<configuration> 
    <property> 
        <name>talend.kerberos.authentication </name> 
        <value>kinit </value>
         <description> Set the Kerberos authentication method to use. Valid values are: kinit or keytab.  </description> 
    </property> 
    <property> 
        <name>talend.kerberos.keytab.principal </name>
        <value>user@BIGDATA.COM </value>
        <description> Set the keytab's principal name.  </description>
    </property> 
    <property>   
        <name>talend.kerberos.keytab.path </name> 
        <value>/kdc/user.keytab </value> 
        <description> Set the keytab's path.  </description> 
    </property> 
    <property> 
        <name>talend.encryption </name> 
        <value>none </value> 
        <description> Set the encryption method to use. Valid values are: none or ssl.  </description> 
    </property> 
    <property> 
        <name>talend.ssl.trustStore.path </name> 
        <value>ssl </value> 
        <description> Set SSL trust store path.  </description> 
    </property> 
    <property> 
        <name>talend.ssl.trustStore.password </name> 
        <value>ssl </value> 
        <description> Set SSL trust store password.  </description> 
    </property> 
</configuration>

The parameters read from these configuration files override the default ones used by the Studio. When a parameter does not exist in these configuration files, the default one is used.

Load function

Select a load function for data to be loaded:

Note that when the file format to be used is PARQUET, you might be prompted to find the specific Parquet jar file and install it into the Studio.

This jar file can be downloaded from Apache's site. For further information about how to install an external jar file, see the article Installing external modules on Talend Help Center (https://help.talend.com).

Input file URI

Fill in this field with the full local path to the input file.

Use S3 endpoint

Select this check box to read data from a given Amazon S3 bucket folder.

Once this Use S3 endpoint check box is selected, you need to enter the following parameters in the fields that appear:

Note that the format of the S3 file is S3N (S3 Native Filesystem).

HCataLog Configuration

Fill the following fields to configure HCataLog managed tables on HDFS (Hadoop distributed file system):

Distribution and Version:

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:

Along with the evolution of Hadoop, please note the following changes:

HCat metastore: Enter the location of the HCatalog's metastore, which is actually Hive's metastore, a system catalog. For further information about Hive and HCatalog, see http://hive.apache.org/.

Database: The database in which tables are placed.

Table: The table in which data is stored.

Partition filter: Fill this field with the partition keys to list partitions by filter.

Enter character, string or regular expression to separate fields for the transferred data.

Compression

Select the Force to compress the output data check box to compress the data when the data is outputted by tPigStoreResult at the end of a Pig process.

Hadoop provides different compression formats that help reduce the space needed for storing files and speed up data transfer. When you need to write and compress data using the Pig program, by default you have to add a compression format as a suffix to the path pointing to the folder in which you want to write data, for example, /user/ychen/out.bz2. However, if you select this check box, the output data will be compressed even if you do not add any compression format to that path, such as /user/ychen/out.

This area is available to the HBaseStorage function. The parameters to be set are:

Zookeeper quorum:

Type in the name or the URL of the Zookeeper service you use to coordinate the transaction between your Studio and your database. Note that when you configure the Zookeeper, you might need to explicitly set the zookeeper.znode.parent property to define the path to the root znode that contains all the znodes created and used by your database; then select the Set Zookeeper znode parent check box to define this property.

Zookeeper client port:

Type in the number of the client listening port of the Zookeeper service you are using.

Table name:

Enter the name of the HBase table you need to load data from.

Load key:

Select this check box to load the row key as the first column of the result schema. In this situation, you must have created this column in the schema.

Mapping:

Complete this table to map the columns of the table to be used with the schema columns you have defined for the data flow to be processed.

Sequence Loader configuration

This area is available only to the SequenceFileLoader function. Since a SequenceFile record consists of binary key/value pairs, the parameters to be set are:

Key column:

Select the Key column of a key/value record.

Value column

Select the Value column of a key/value record.

Die on subjob error

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

Tez lib

Select how the Tez libraries are accessed:

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:

Register jar

Click the button to add rows to the table and from these rows, browse to the jar files to be added. For example, in order to register a jar file called piggybank.jar, click the button once to add one row, then click this row to display the browse button, and click this button to browse to the piggybank.jar file following the [Select Module] wizard.

Use this table to define UDFs (User-Defined Functions), especially those requiring alias such as Apache DataFu Pig functions, to be executed when loading data.

Click the button to add as many rows as you need and specify an alias and a UDF in the relevant fields for each row.

If your Job includes a tPigMap component, once you have defined UDFs for this component in the tPigMap, this table is automatically filled. Likewise, once you have defined UDFs in this table, the Define functions table in the tPigMap component's Map Editor is automatically filled.

For information on how to define UDFs when mapping Pig flows, see the section on mapping Big Data flows of the Talend Open Studio for Big Data Getting Started Guide.

For more information on Apache DataFu Pig, see http://datafu.incubator.apache.org/.

Pig properties

Talend Studio uses a default configuration for its Pig engine to perform operations. 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 example, the default_parallel key used in Pig could be set as 20.

Add and set more HBaseStorage loader options in this table. The options are:

gt: the minimum key value;

lt: the maximum key value;

gte: the minimum key value (included);

lte: the maximum key value (included);

limit: maximum number of rows to retrieve per region;

caching: number of rows to cache;

caster: the converter to use for reading values out of HBase. For example, HBaseBinaryConverter.

HCatalog Configuration

Define the jars to register for HCatalog

This check box appears when you are using tHCatLoader, while you can leave it clear as the Studio registers the required jar files automatically. In case any jar file is missing, you can select this check box to display the Register jar for HCatalog table and set the correct path to that missing jar.

Path separator in server

Leave the default value of the Path separator in server as it is, unless you have changed the separator used by your Hadoop distribution's host machine for its PATH variable or in other words, that separator is not a colon (:). In that situation, you must change this value to the one you are using in that host.

Mapred job map memory mb and Mapred job reduce memory mb

If the Hadoop distribution to be used is Hortonworks Data Platform V1.2 or Hortonworks Data Platform V1.3, you need to set proper memory allocations for the map and reduce computations to be performed by the Hadoop system.

In that situation, you need to enter the values you need in the Mapred job map memory mb and the Mapred job reduce memory mb fields, respectively. By default, the values are both 1000 which are normally appropriate for running the computations.

If the distribution is YARN, then the memory parameters to be set become Map (in Mb), Reduce (in Mb) and ApplicationMaster (in Mb), accordingly. These fields allow you to dynamically allocate memory to the map and the reduce computations and the ApplicationMaster of YARN.

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 further information about variables, see Talend Studio User Guide.

Usage

This component is always used to start a Pig process and needs tPigStoreResult at the end to output its data.

In the Map/Reduce mode, you need only configure the Hadoop connection for the first tPigLoad component of a Pig process (a subjob), and any other tPigLoad component used in this process reuses automatically that connection created by that first tPigLoad 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

Knowledge of Pig scripts is required. If you select HCatLoader as the load function, knowledge of HCataLog DDL(HCataLog Data Definition Language, a subset of Hive Data Definition Language) is required. For further information about HCataLog DDL, see https://cwiki.apache.org/confluence/display/Hive/HCatalog.