July 30, 2023

tHCatalogOperation – Docs for ESB 7.x

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tHCatalogOperation

Prepares the HCatalog managed database/table/partition to be processed.

tHCatalogOperation manages the data
stored in HCatalog managed Hive database/table/partition.

tHCatalogOperation Standard properties

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

The Standard
tHCatalogOperation component belongs to the Big Data family.

The component in this framework is available in all Talend products with Big Data
and in Talend Data Fabric.

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.

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 HD
    Insightcluster and the Windows Azure Storage service of that cluster in the
    areas that are displayed. For
    detailed explanation about these parameters, search for configuring the
    connection manually on Talend Help Center (https://help.talend.com).

  • If you select Amazon EMR, find more details about Amazon EMR getting started in
    Talend Help Center (https://help.talend.com).

  • 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
    .

  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 Hortonworks.

HCatalog version

Select the version of the Hadoop distribution you are using. The available
options vary depending on the component you are using.

Templeton hostname

Fill this field with the URL of Templeton Webservice.

Note:

Templeton is a webservice API for HCatalog. It has been renamed to WebHCat by the
Apache community. This service facilitates the access to HCatalog and the related Hadoop
elements such as Pig. For further information about Templeton (WebHCat), see https://cwiki.apache.org/confluence/display/Hive/WebHCat+UsingWebHCat.

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 has been renamed to WebHCat by the
Apache community. This service facilitates the access to HCatalog and the related Hadoop
elements such as Pig. For further information about Templeton (WebHCat), see https://cwiki.apache.org/confluence/display/Hive/WebHCat+UsingWebHCat.

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.

  • If this cluster is a MapR cluster of the version 5.0.0 or later, you can set the
    MapR ticket authentication configuration in addition or as an alternative by following
    the explanation in Connecting to a security-enabled MapR.

    Keep in mind that this configuration generates a new MapR security ticket for the username
    defined in the Job in each execution. If you need to reuse an existing ticket issued for the
    same username, leave both the Force MapR ticket
    authentication     check box and the Use Kerberos
    authentication     check box clear, and then MapR should be able to automatically
    find that ticket on the fly.

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 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. This keytab file must be stored in the machine in
which your Job actually runs, for example, on a Talend Jobserver.

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.

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.

If you are reading a non-partitioned table, leave this field empty.

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 https://cwiki.apache.org/confluence/display/Hive/RCFile.

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

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 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 documentation about HCatalog: https://cwiki.apache.org/confluence/display/Hive/HCatalog.

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

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

Managing HCatalog tables on Hortonworks Data Platform

This scenario applies only to Talend products with Big Data.

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.

    tHCatalogOperation_1.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.

    tHCatalogOperation_2.png

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

    tHCatalogOperation_3.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.

    tHCatalogOperation_4.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.

    tHCatalogOperation_5.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. If you are using WebHDFS, the location should be
    webhdfs://masternode:portnumber; WebHDFS with SSL is not
    supported yet.
  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.

    tHCatalogOperation_6.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.

    tHCatalogOperation_7.png

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

    tHCatalogOperation_8.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.

    tHCatalogOperation_9.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.

tHCatalogOperation_10.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:

tHCatalogOperation_11.png

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

tHCatalogOperation_12.png

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