August 17, 2023

tHCatalogOperation – Docs for ESB 5.x

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tHCatalogOperation

tHCatalogOperation_icon32_white.png

Warning

This component will be available in the Palette of
Talend Studio on the condition that you have subscribed to one of
the Talend
solutions with Big Data.

tHCatalogOperation Properties

Component family

Big Data / HCatalog

  

Function

This component allows you to manage the data stored in HCatalog
managed Hive database/table/partition.

Purpose

The tHCatalogOperation component
prepares the HCatalog managed database/table/partition to be
processed.

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.

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 dotbutton.png 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 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.
 

HCatalog 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:

  • 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    .

Templeton Configuration

Templeton hostname

Fill this field with the URL of Templeton Webservice.

Note

Templeton is a webservice API for HCatalog. It facilitates the access to HCatalog and
the related Hadoop elements such as Pig. For further information about Templeton, see
http://people.apache.org/~thejas/templeton_doc_latest.

 

Templeton port

Fill this field with the port of URL of Templeton Webservice. By
default, the value for this field is 50111.

Note

Templeton is a webservice API for HCatalog. It facilitates the access to HCatalog and
the related Hadoop elements such as Pig. For further information about Templeton, see
http://people.apache.org/~thejas/templeton_doc_latest.

 

Use kerberos authentication

If you are accessing the Hadoop cluster running with Kerberos security, select this check
box, then, enter the Kerberos principal name for the NameNode in the field displayed. This
enables you to use your user name to authenticate against the credentials stored in
Kerberos.

This check box is available depending on the Hadoop distribution you are connecting
to.
  Use a keytab to authenticate

Select the Use a keytab to authenticate check box to log
into a Kerberos-enabled Hadoop system using a given keytab file. A keytab file contains
pairs of Kerberos principals and encrypted keys. You need to enter the principal to be used
in the Principal field and the access path to the keytab
file itself in the Keytab field.

Note that the user that executes a keytab-enabled Job is not necessarily the one a
principal designates but must have the right to read the keytab file being used. For
example, the user name you are using to execute a Job is user1 and the principal to be used is guest; in this situation, ensure that user1 has the right to read the keytab file to be used.

 

Operation on

Select an object from the list for the DB operation as
follows:

Database: The HCatalog managed
database in HDFS.

Table: The HCatalog managed table
in HDFS.

Partition: The partition
specified by the user.

 

Operation

Select an action from the list for the DB operation. For further
information about the DB operation in HDFS, see https://cwiki.apache.org/Hive/.
  Create the table only it doesn’t exist
already

Select this check box to avoid creating duplicate table when you
create a table.

Note

This check box is enabled only when you have selected
Table from the
Operation on
list.

HCatalog Configuration

Database

Fill this field with the name of the database in which the
HCatalog managed tables are placed.

 

Table

Fill this field to operate on one or multiple tables in a database
or on a specified HDFS location.

Note

This field is enabled only when you have selected
Table from the
Operation on list. For
further information about the operation on Table, see https://cwiki.apache.org/Hive/.

 

Partition

Fill this field to specify one or more partitions for the
partition operation on a specified table. When you specify multiple
partitions, use comma to separate every two partitions and use
double quotation marks to quote the partition string.

Note

This field is enabled only when you select Partition from the Operation on list. For further
information about the operation on Partition, see https://cwiki.apache.org/Hive/.
  Username

Fill this field with the username for the DB
authentication.

 

Database location

Fill this field with the location of the database file in HDFS.

Note

This field is enabled only when you select Database from the Operation on list.

 

Database description

The description for the database to be created.

Note

This field is enabled only when you select Database from the Operation on list.
  Create an external table

Select this field to create an external table in an alternative
path defined in the Set HDFS
location field in the Advanced
settings view. For further information about creating
external table, see https://cwiki.apache.org/Hive/.

Note

This check box is enabled only when you select Table from the Operation on list and Create/Drop and create/Drop if exist and
create from the Operation list.
  Format

Select a file format from the list to specify the format of the
external table you want to create:

TEXTFILE: Plain text
files.

RCFILE: Record Columnar files.
For further information about RCFILE, see http://hive.apache.org/javadocs/r0.10.0/api/org/apache/hadoop/hive/ql/io/RCFile.html.

Note

RCFILE is only available
starting with Hive 0.6.0. This list is enabled only when you
select Table from the
Operation on list and
Create/Drop and create/Drop if
exist and create from the Operation list.
  Set partitions

Select this check box to set the partition schema by clicking the
Edit schema to the right of
Set partitions check box. The
partition schema is either built-in or remote in the Repository.

Note

This check box is enabled only when you select Table from the Operation on list and Create/Drop and
create/Drop if exist and
create from the Operation list. You must follow the rules of
using partition schema in HCatalog managed tables. For more
information about the rules in using partition schema, see https://cwiki.apache.org/confluence/display/Hive/HCatalog.

 

 

Built-in: The schema will be
created and stored locally for this component only. Related topic:
see Talend Studio User Guide.

 

 

Repository: The schema already
exists and is stored in the Repository, hence can be reused in
various projects and Job designs. Related topic: see
Talend Studio User Guide.
  Set the user group to use

Select this check box to specify the user group.

Note

This check box is enabled only when you select Drop/Drop
if exist/Drop and
create/Drop if exist
and create from the Operation list. By default, the value for
this field is root. For
more information about the user group in the server, contact
your system administrator.
  Option

Select a clause when you drop a database.

Note

This list is enabled only when you select Database from the Operation on list and Drop/Drop
if exist/Drop and
create/Drop if exist
and create from the Operation list. For more information about
Drop operation on
database, see https://cwiki.apache.org/Hive/.
  Set the permissions to use

Select this check box to specify the permissions needed by the
operation you select from the Operation list.

Note

This check box is enabled only when you select Drop/Drop
if exist/Drop and
create/Drop if exist
and create from the Operation list. By default, the value for
this field is rwxrw-r-x.
For more information on user permissions, contact your
system administrator.
  Set File location

Enter the directory in which partitioned data is stored.

Note

This check box is enabled only when you select Partition from the Operation on list and Create/Drop
and create/Drop if
exist and create from the Operation list. For further
information about storing partitioned data in HDFS, see
https://cwiki.apache.org/Hive/.

 

Die on error

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

Fill this field with the comment for the table you want to create.

Note

This field is enabled only when you select Table from the Operation on list and Create/Drop
and create/Drop if
exist and create from the Operation list in the Basic settings view.
  Set HDFS location

Select this check box to specify an HDFS location to which the
table you want to create is saved. Deselect it to save the table you
want to create in the warehouse directory defined in the key
hive.metastore.warehouse.dir
in Hive configuration file hive-site.xml.

Note

This check box is enabled only when you select Table from the Operation on list and Create/Drop
and create/Drop if
exist and create from the Operation list in the Basic settings view. For further
information about saving data in HDFS, see https://cwiki.apache.org/Hive/.
  Set row format(terminated by)

Select this check box to use and define the row formats when you
want to create a table:

Field: Select this check box to
use Field as the row format. The
default value for this field is “u0001”. You can also specify a customized char in
this field.

Collection Item: Select this
check box to use Collection Item as
the row format. The default value for this field is “u0002”. You can also specify a
customized char in this field.

Map Key: Select this check box to
use Map Key as the row format. The
default value for this field is “u0003”. You can also specify a customized char in
this field.

Line: Select this check box to
use Line as the row format. The
default value for this field is ”
“. You can also specify a customized char in this
field.

Note

This check box is enabled only when you select Table from the Operation on list and Create/Drop
and create/Drop if
exist and create from the Operation list in the Basic settings view. For further
information about row formats in the HCatalog managed table,
see https://cwiki.apache.org/Hive/.
  Properties

Click [+] to add one or more
lines to define table properties. The table properties allow you to
tag the table definition with your own metadata key/value pairs.
Make sure that values in both Key
row and Value row must be quoted in
double quotation marks.

Note

This table is enabled only when you select Database/Table from the Operation on list and Create/Drop and
create/Drop if exist
and create from the Operation list in the Basic settings view. For further information
about table properties, see https://cwiki.apache.org/Hive/.
Retrieve the HCatalog logs Select this check box to retrieve log files generated
during HCatalog operations.
  Standard Output Folder

Browse to, or enter the directory where the log files are
stored.

Note

This field is enabled only when you selected Retrieve the HCatalog logs check
box.
 

Error Output Folder

Browse to, or enter the directory where the error log files are stored.

Note

This field is enabled only when you selected Retrieve the HCatalog logs check
box.
 

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 commonly used in a single-component
Subjob.

HCatalog is built on top of the Hive metastore to provide read and write interface for Pig and MapReduce, so that the latter systems can use the metadata of Hive to easily read and write data in HDFS.

For further information, see Apache’s documentation about HCatalog. For example, https://cwiki.apache.org/confluence/display/HCATALOG/Design+Document+-+Java+APIs+for+HCatalog+DDL+Commands.

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. 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.

Log4j

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

When Use kerberos authentication
is selected, the component cannot work with IBM JVM.

Scenario: HCatalog table management on Hortonworks Data Platform

This scenario describes a six-component Job that includes the common operations for
the HCatalog table management on Hortonworks Data Platform. Sub-sections in this
scenario covers DB operations including:

  • Creating a table to the database in HDFS;

  • Writing data to the HCatalog managed table;

  • Writing data to the partitioned table using tHCatalogLoad;

  • Reading data from the HCatalog managed table;

  • Outputting the data read from the table in HDFS.

Note

Knowledge of Hive Data Definition Language and HCatalog Data Definition
Language is required. For further information about Hive Data Definition
Language, see https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL.
For further information about HCatalog Data Definition Language, see https://cwiki.apache.org/confluence/display/HCATALOG/Design+Document+-+Java+APIs+for+HCatalog+DDL+Commands.

Setting up the Job

  1. Drop the following components from the Palette to the design workspace: tHCatalogOperation, tHCatalogLoad, tHCatalogInput, tHCatalogOutput, tFixedFlowInput, and tFileOutputDelimited.

    use_case_thcatalogload1.png

  2. Right-click tHCatalogOperation to connect
    it to tFixedFlowInput component using a
    Trigger>OnSubjobOk
    connection.

  3. Right-click tFixedFlowInput to connect it
    to tHCatalogOutput using a Row > Main
    connection.

  4. Right-click tFixedFlowInput to connect it
    to tHCatalogLoad using a Trigger > OnSubjobOk connection.

  5. Right-click tHCatalogLoad to connect it
    to the tHCatalogInput component using a
    Trigger > OnSubjobOk connection.

  6. Right-click tHCatalogInput to connect it
    to tFileOutputDelimited using a Row > Main
    connection.

Creating a table in HDFS

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

    use_case_thcatalogload2.png

  2. Click Edit schema to define the schema
    for the table to be created.

    use_case_thcatalogload3.png

  3. Click [+] to add at least one column to
    the schema and click OK when you finish
    setting the schema. In this scenario, the columns added to the schema are:
    name, country and age.

  4. Fill the Templeton hostname field with
    URL of the Templeton webservice you are using. In this scenario, fill this
    field with “192.168.0.131“.

  5. Fill the Templeton port field with the
    port for Templeton hostname. By default,
    the value for this field is “50111“

  6. Select Table from the Operation on list and Drop
    if exist and create     from the Operation list to create a table in HDFS.

  7. Fill the Database field with an existing
    database name in HDFS. In this scenario, the database name is “talend“.

  8. Fill the Table field with the name of the
    table to be created. In this scenario, the table name is “Customer“.

  9. Fill the Username field with the username
    for the DB authentication.

  10. Select the Set the user group to use
    check box to specify the user group. The default user group is “root“, you need to specify the value for this
    field according to real practice.

  11. Select the Set the permissions to use
    check box to specify the user permission. The default value for this field
    is “rwxrwxr-x“.

  12. Select the Set partitions check box to
    enable the partition schema.

  13. Click the Edit schema button next to
    the Set partitions check box to define
    the partition schema.

  14. Click [+] to add one column to the schema
    and click OK when you finish setting the
    schema. In this scenario, the column added to the partition schema is:
    match_age.

Writing data to the existing table

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

    use_case_thcatalogload4.png

  2. Click Edit schema to define a same schema
    as the one you defined in tHCatalogOperation.

  3. Fill the Number of rows field with
    integer 8.

  4. Select Use Inline Table in the Mode area.

  5. Click [+] to add new lines in the inline
    table.

  6. Double-click tHCatalogOutput to open its
    Basic settings view.

    use_case_thcatalogload5.png

  7. Click Sync columns to retrieve the schema
    defined in the preceding component.

  8. Fill the NameNode URI field with the URI
    to the NameNode. In this scenario, this URL is “192.168.0.131“.

  9. Fill the File name field with the HDFS
    location of the file you write data to. In this scenario, the file location
    is “/user/hdp/Customer/Customer.csv“.

  10. Select Overwrite from the Action list.

  11. Fill the Templeton hostname field with
    URL of the Templeton webservice you are using. In this scenario, fill this
    field with “192.168.0.131“.

  12. Fill the Templeton port field with the
    port for Templeton hostname. By default,
    the value for this field is “50111“

  13. Fill the Database field, the Table field, the Username field with the same value you specified in
    tHCatalogOperation.

  14. Fill the Partition field with “match_age=27“.

  15. Fill the File location field with the
    HDFS location to which the table will be saved. In this example, use
    “hdfs://192.168.0.131:8020/user/hdp/Customer“.

Writing data to the partitioned table using tHCatalogLoad

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

    use_case_thcatalogload6.png

  2. Fill the Partition field with “match_age=26“.

  3. Do the rest of the settings in the same way as configuring tHCatalogOperation.

Reading data from the table in HDFS

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

    use_case_thcatalogload8.png

  2. Click Edit schema to define the schema of
    the table to be read from the database.

    use_case_thcatalogload9.png

  3. Click [+] to add at least one column to
    the schema. In this scenario, the columns added to the schema are age and name.

  4. Fill the Partition field with “match_age=26“.

  5. Do the rest of the settings in the same way as configuring tHCatalogOperation.

Outputting the data read from the table in HDFS to the console

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

    use_case_thcatalogload10.png

  2. Click Sync columns to retrieve the schema
    defined in the preceding component.

  3. Select Table from the Mode area.

Job execution

Press CTRL+S to
save your Job and F6 to execute it.

use_case_thcatalogload11.png

The data of the restricted table read from the HDFS is displayed onto the
console.

Type in http://talend-hdp:50075/browseDirectory.jsp?dir=/user/hdp/Customer&namenodeInfoPort=50070
to the address bar of your browser to view the table you created:

use_case_thcatalogload13.png

Click the Customer.csv link to view the content
of the table you created.

use_case_thcatalogload12.png
Document get from Talend https://help.talend.com
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