tImpalaCreateTable properties - 6.1

Talend Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Data Integration
Talend Data Management Platform
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for Big Data
Talend Open Studio for Data Integration
Talend Open Studio for Data Quality
Talend Open Studio for ESB
Talend Open Studio for MDM
Talend Real-Time Big Data Platform
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Component family

Big Data / Impala

 

Function

This component connects to the Impala database to be used and creates an Impala table that is dedicated to data of the format you specify.

Purpose

This component is used to create Impala tables that fit a wide range of Impala data formats.

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.

Use an existing connection

Select this check box and in the Component List click the relevant connection component to reuse the connection details you already defined.

Note

When a Job contains the parent Job and the child Job, if you need to share an existing connection between the two levels, for example, to share the connection created by the parent Job with the child Job, you have to:

  1. In the parent level, register the database connection to be shared in the Basic settings view of the connection component which creates that very database connection.

  2. In the child level, use a dedicated connection component to read that registered database connection.

For an example about how to share a database connection across Job levels, see Talend Studio User Guide.

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:

  • If available in this Distribution drop-down list, the Microsoft HD Insight option allows you to use a Microsoft HD Insight cluster. For this purpose, you need to configure the connections to the WebHCat service, the HD Insight service and the Windows Azure Storage service of that cluster in the areas that are displayed. A demonstration video about how to configure this connection is available in the following link: https://www.youtube.com/watch?v=A3QTT6VsNoM.

  • The Custom option allows you to connect to a cluster different from any of the distributions given in this list, that is to say, to connect to a cluster not officially supported by Talend.

In order to connect to a custom distribution, once selecting Custom, click the button to display the dialog box in which you can alternatively:

  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.

    In Talend Exchange, members of Talend community have shared some ready-for-use configuration zip files which you can download from this Hadoop configuration list and directly use them in your connection accordingly. However, because of the ongoing evolution of the different Hadoop-related projects, you might not be able to find the configuration zip corresponding to your distribution from this list; then it is recommended to use the Import from existing version option to take an existing distribution as base to add the jars required by your distribution.

    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 the 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.

    Note

    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 Connecting to a custom Hadoop distribution.

 

Impala 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:

  • If you use Hortonworks Data Platform V2.2, the configuration files of your cluster might be using environment variables such as ${hdp.version}. If this is your situation, you need to set the mapreduce.application.framework.path property in the Hadoop properties table of this component with the path value explicitly pointing to the MapReduce framework archive of your cluster. For example:

    mapreduce.application.framework.path=/hdp/apps/2.2.0.0-2041/mapreduce/mapreduce.tar.gz#mr-framework
  • If you use Hortonworks Data Platform V2.0.0, the type of the operating system for running the distribution and a Talend Job must be the same, such as Windows or Linux. Otherwise, you have to use Talend Jobserver to execute the Job in the same type of operating system in which the Hortonworks Data Platform V2.0.0 distribution you are using is run. For further information about Talend Jobserver, see Talend Installation Guide.

 

Host

Database server IP address.

 

Port

Listening port number of DB server.

 

Database

Fill this field with the name of the database.

 

Username and Password

DB user authentication data.

Authentication

Use kerberos authentication

If you are accessing an Impala system running with Kerberos security, select this check box and then enter the Kerberos principal of this Impala system.

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

 

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:

  • View schema: choose this option to view the schema only.

  • Change to built-in property: choose this option to change the schema to Built-in for local changes.

  • Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.

 

 

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.

When the schema to be reused has default values that are integers or functions, ensure that these default values are not enclosed within quotation marks. If they are, you must remove the quotation marks manually.

For more details, see https://help.talend.com/display/KB/Verifying+default+values+in+a+retrieved+schema.

 

Table Name

Name of the table to be created.

 

Action on table

Select the action to be carried out for creating a table.

 

Format

Select the data format to which the table to be created is dedicated.

The available data formats vary depending on the version of the Hadoop distribution you are using.

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.

  • When the connection mode to Hive is Embedded, the Job is run in your local machine and calls this jar installed in the Studio.

  • When the connection mode to Hive is Standalone, the Job is run in the server hosting Hive and this jar file is sent to the HDFS system of the cluster you are connecting to. Therefore, ensure that you have properly defined the NameNode URI in the corresponding field of the Basic settings view.

This jar file can be downloaded from Apache's site. For further information about how to install an external jar file, see https://help.talend.com/display/KB/How+to+install+external+modules+in+the+Talend+products.

  Set partitions

Select this check box to add partition columns to the table to be created. Once selecting it, you need to define the schema of the partition columns you need to add.

 

Set file location

If you want to create an Impala table in a directory other than the default one, select this check box and enter the directory in HDFS you want to use to hold the table content.

This is typical useful when you need to create an external Impala table by selecting the Create an external table check box in the Advanced settings tab.

 

Use S3 endpoint

The Use S3 endpoint check box is displayed when you have selected the Set file location check box to create an external Impala table.

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

  • S3 bucket: enter the name of the bucket in which you need to create the table.

  • Access key and Secret key: enter the authentication information required to connect to the Amazon S3 bucket to be used.

    To enter the password, click the [...] button next to the password field, and then in the pop-up dialog box enter the password between double quotes and click OK to save the settings.

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

Since an Impala table created in S3 is actually an external table, this Use S3 endpoint check box must be used with the Create an external table case being selected.

Row format

Set Delimited row format

Select this check box to use the Delimited row format as the storage format of data in the Impala table to be created. Once selecting it, you can further to specify the delimiter(s) for the data you need to load to the table.

  • The Field delimiter is to separate fields of the data.

  • The Line delimiter is to separate data rows.

In defining the Field delimiter, you can as well define the escaping character you need to use by selecting the Escape check box and entering that character. Otherwise, the backward slash (\) is used by default.

Note that this check box is not available when you have selected AVRO from the Format list.

 

Die on error

Select this check box to kill the Job when an error occurs.

Advanced settings

Like table

Select this check box and enter the name of the Impala table you want to copy. This allows you to copy the definition of an existing table without copying its data.

For further information about the Like parameter, see Cloudera's information about Impala's Data Definition Language.

 

Create an external table

Select this check box to make the table to be created an external Impala table. This kind of Impala table leaves the raw data where it is if the data is in HDFS.

An external table is usually the better choice for accessing shared data existing in a file system.

For further information about an external Impala table, see Cloudera's documentation about Impala.

 

Table comment

Enter the description you want to use for the table to be created.

 

As select

Select this check box and enter the As select statement for creating an Impala table that is based on a Select statement.

 

Table properties

Add any custom Impala table properties you want to override the default ones used by the Hadoop engine of the Studio.

 

tStatCatcher Statistics

Select this check box to collect log data at the 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 database connection dynamically from multiple connections planned in your Job. This feature is useful when you need to access database tables having the same data structure but in different databases, 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

This component works standalone.

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 the 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. For further information, see the following link from MapR: http://www.mapr.com/blog/basic-notes-on-configuring-eclipse-as-a-hadoop-development-environment-for-mapr.

    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. This argument provides to the 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 the Studio the data stored in MapR. For further information about how to set this argument, see the section describing how to view data of Talend Big Data Getting Started Guide.

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