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Component family
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Big Data / Impala
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Function
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tImpalaInput is the dedicated
component to the Impala database (the Impala data warehouse system).
It executes the given Impala SQL query in order to extract the data
of interest from Impala. It provides the SQLBuilder tool to help you
write your Impala SQL statements easily.
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Purpose
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tImpalaInput executes the select
queries to extract the corresponding data and sends the data to the
component that follows.
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Basic settings
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Property type
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Either Built-in or Repository.
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Built-in: No property data stored
centrally.
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Repository : Select the
repository file in which the properties are stored. The fields that
follow are completed automatically using the data retrieved. |
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Use an existing connection
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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:
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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.
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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.
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Version
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Distribution
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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:
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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
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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:
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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.
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Select Import from zip to import a custom
distribution zip that, for example, you can download from http://www.talendforge.org/exchange/index.php.
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 an step-by-step example about how to connect to a custom distribution and
share this connection, see Connecting to a custom Hadoop distribution.
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Impala version
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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:
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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:
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mapreduce.application.framework.path=/hdp/apps/2.2.0.0-2041/mapreduce/mapreduce.tar.gz#mr-framework |
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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
and Upgrade Guide.
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Host
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Database server IP address.
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Port
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Listening port number of DB server.
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Database
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Fill this field with the name of the database.
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Username
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DB user authentication data.
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Authentication
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Use kerberos authentication
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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.
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Schema and Edit
Schema
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A schema is a row description. It defines the number of fields 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:
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View schema: choose this option to view the
schema only.
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Change to built-in property: choose this option
to change the schema to Built-in for local
changes.
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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.
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Built-in: The schema is created
and stored locally for this component only. Related topic: see
Talend Studio
User Guide.
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Repository: The schema already
exists and is stored in the Repository, hence can be reused. Related
topic: see Talend Studio
User Guide.
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Table Name
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Name of the table to be processed.
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Query type
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Either Built-in or Repository.
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Built-in: Fill in manually the
query statement or build it graphically using SQLBuilder
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Repository: Select the relevant
query stored in the Repository. The Query field gets accordingly
filled in.
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Guess Query
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Click the Guess Query button to
generate the query which corresponds to your table schema in the
Query field.
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Guess schema
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Click this button to retrieve the schema from the table.
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Query
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Enter your DB query paying particularly attention to properly
sequence the fields in order to match the schema definition.
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Advanced settings
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Trim all the String/Char columns
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Select this check box to remove leading and trailing whitespace
from all the String/Char columns.
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Trim column
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Remove leading and trailing whitespace from defined
columns.
Note
Clear the Trim all the String/Char
columns check box to enable Trim column in this field.
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tStatCatcher Statistics
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Select this check box to collect log data at the component
level.
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Dynamic settings
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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 more information on Dynamic settings and context
variables, see Talend Studio User Guide.
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Global Variables
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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.
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Usage
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This component offers the benefit of flexible DB queries and covers all possible Impala
SQL queries.
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Prerequisites
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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.
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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
hadoophadoop-VERSIONlib
ative. For example, the library for
Windows is lib
ativeMapRClient.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.
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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.
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