tImpalaCreateTable – Docs for ESB 5.x

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.

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:

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:

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 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.

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.

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.

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:

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.

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 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.

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