August 16, 2023

tPigFilterRow – Docs for ESB 6.x

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tPigFilterRow

Applies filtering conditions on one or more specified columns, in a Pig process, in
order to split or filter data from a relation.

The tPigFilterRow filters or splits
the input flow in a Pig process based on conditions set on given column(s).

tPigFilterRow Standard properties

These properties are used to configure tPigFilterRow running in the Standard Job framework.

The Standard
tPigFilterRow component belongs to the Big Data and the Processing families.

The component in this framework is available when you are using one of the Talend solutions with Big Data.

Basic settings

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.

Filter configuration

Click the Add button beneath the
Filter configuration table to
set one or more filter conditions.

Note that when the column to be used by a condition is of the
string type, the text to be
entered in the Value column must be
surrounded by both single and double quotation marks (for example,
“‘California'”), because the
double quotation marks are required by
Talend
‘s code generator and the single
quotation marks required by Pig’s grammar.

Note:

This table disappears if you select Use
advanced filter.

Use advanced filter

Select this check box to define advanced filter condition by
entering customized filter expression in the Filter field.

Advanced settings

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

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

Usage rule

This component is commonly used as an intermediate step in a Pig
process.

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
    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.

  • 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 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 install a Hadoop distribution, see the manuals
corresponding to the Hadoop distribution you are using.

Limitation

Knowledge of Pig scripts is required.

Scenario: Filtering rows of data based on a condition and saving the result to a
local file

This scenario applies only to a Talend solution with Big Data.

This scenario describes a four-component Job that filters a list of customers to find
out customers from a particular country, and saves the result list to a local file.
Before the input data is filtered, duplicate entries are first removed from the list.

The input file contains three columns: Name,
Country, and Age, and it has some duplicate entries, as shown below:

Dropping and linking components

  1. Drop the following components from the Palette to the design workspace: tPigLoad, tPigDistinct,
    tPigFilterRow, and tPigStoreResult.
  2. Right-click tPigLoad, select Row > Pig
    Combine     from the contextual menu, and click tPigDistinct to link these two components.
  3. Repeat this operation to link tPigDistinct to tPigFilterRow, and tPigFilterRow to tPigStoreResult using Row >
    Pig Combine connections to form a Pig
    process.

    Use_Case_tPigFilterRow1.png

Configuring the components

Loading the input data and removing duplicates

  1. Double-click tPigLoad to open its
    Basic settings view.

    Use_Case_tPigFilterRow2.png

  2. Click the […] button next to Edit schema to open the [Schema] dialog box.

    Use_Case_tPigFilterRow3.png

  3. Click the [+] button to add three columns
    according to the data structure of the input file: Name
    (string), Country (string) and Age
    (integer), and then click OK to save the
    setting and close the dialog box.
  4. Click Local in the Mode area.
  5. Fill in the Input file URI field with the
    full path to the input file.
  6. Select PigStorage from the Load function list, and leave rest of the
    settings as they are.
  7. Double-click tPigDistinct to open its
    Basic settings view, and click
    Sync columns to make sure that the
    input schema structure is correctly propagated from the preceding
    component.

    This component will remove any duplicates from the data flow.

Configuring the filter

  1. Double-click tPigFilterRow to open its
    Basic settings view.

    Use_Case_tPigFilterRow4.png

  2. Click Sync columns to make sure that the
    input schema structure is correctly propagated from the preceding
    component.
  3. Select Use advanced filter and fill in
    the Filter field with filter
    expression:

    This filter expression selects rows of data that contains “PuertoRico” in
    the Country column.

Configuring the file output

  1. Double-click tPigStoreResult to open its
    Basic settings view.

    Use_Case_tPigFilterRow5.png

  2. Click Sync columns to make sure that the
    input schema structure is correctly propagated from the preceding
    component.
  3. Fill in the Result file field with the
    full path to the result file.
  4. If the target file already exists, select the Remove
    result directory if exists     check box.
  5. Select PigStorage from the Store function list, and leave rest of the
    settings as they are.

Saving and executing the Job

  1. Press Ctrl+S to save your Job.
  2. Press F6 or click the Run button on the Run tab to run the Job.

    The result file contains the information of customers from the specified
    country.
    Use_Case_tPigFilterRow6.png

Document get from Talend https://help.talend.com
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Docs 6.x
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