tMapRDBInput Standard properties

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

The Standard tMapRDBInput component belongs to the Big Data and the Databases NoSQL families.

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 where the properties are stored. The properties are stored centrally under the Hadoop Cluster node of the Repository tree.
Use an existing connection	Select this check box and in the Component List drop-down list, select the desired connection component to reuse the connection details you already defined.
Distribution and Version	Select the MapR distribution to be used. Only MapR V5.2 onwards is supported by the MapRDB components. If the distribution you need to use with your MapRDB database is not officially supported by this MapRBD component, that is to say, this distribution is MapR but is not listed in the Version drop-down list of this components or this distribution is not MapR at all, select Custom. 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. 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. 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 Talend 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. Information noteNote: 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.
Hadoop version of the distribution	This list is displayed only when you have selected Custom from the distribution list to connect to a cluster not yet officially supported by Talend Studio. In this situation, you need to select the Hadoop version of this custom cluster, that is to say, Hadoop 1 or Hadoop 2.
Zookeeper quorum	Type in the name or the URL of the ZooKeeper service you use to coordinate the transaction between your Talend Studio and your database. Note that when you configure the ZooKeeper, you might need to explicitly set the zookeeper.znode.parent property to define the path to the root Znode that contains all the Znodes created and used by your database; then select the Set Zookeeper znode parent check box to define this property.
Zookeeper client port	Type in the number of the client listening port of the ZooKeeper service you are using.
Use kerberos authentication	If the database to be used is running with Kerberos security, select this check box, then, enter the principal names in the HBase Master principal and HBase Region Server principal fields. You should be able to find the information in the hbase-site.xml file of the cluster to be used. If you need to use a Kerberos keytab file to log in, select Use a keytab to authenticate. 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 username 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.
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. When you create a Spark Job, avoid the reserved word `line` when naming the fields. 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.
	Repository: You have already created the schema and stored it in the Repository. You can reuse it in various projects and Job designs.
Set table Namespace mappings	Enter the string to be used to construct the mapping between an Apache HBase table and a MapR table. For the valid syntax you can use, see http://doc.mapr.com/display/MapR40x/Mapping+Table+Namespace+Between+Apache+HBase+Tables+and+MapR+Tables.
Table name	Type in the name of the table from which you need to extract columns.
Define a row selection	Select this check box and then in the Start row and the End row fields, enter the corresponding row keys to specify the range of the rows you want the current component to extract. Different from the filters you can set using Is by filter requiring the loading of all records before filtering the ones to be used, this feature allows you to directly select only the rows to be used.
Mapping	Complete this table to map the columns of the table to be used with the schema columns you have defined for the data flow to be processed.

Advanced settings

tStatCatcher Statistics	Select this check box to collect log data at the component level.
Properties	If you need to use custom configuration for your database, complete this table with the property or properties to be customized. Then at runtime, the customized property or properties will override the corresponding ones used by Talend Studio. For example, you need to define the value of the dfs.replication property as 1 for the database configuration. Then you need to add one row to this table using the plus button and type in the name and the value of this property in this row. Information noteNote: This table is not available when you are using an existing connection by selecting the Using an existing connection check box in the Basic settings view.
Is by filter	Select this check box to use filters to perform fine-grained data selection from your database, such as selection of keys, or values, based on regular expressions. Once selecting it, the Filter table that is used to define filtering conditions becomes available. This feature leverages filters provided by HBase and subject to constraints explained in Apache HBase documentation. Therefore, advanced knowledge of HBase is required to make full use of these filters.
Logical operation	Select the operator you need to use to define the logical relation between filters. This available operators are: And: every defined filtering conditions must be satisfied. It represents the relationship FilterList.Operator.MUST_PASS_ALL Or: at least one of the defined filtering conditions must be satisfied. It represents the relationship: FilterList.Operator.MUST_PASS_ONE
Filter	Click the button under this table to add as many rows as required, each row representing a filter. The parameters you may need to set for a filter are: Filter type: the drop-down list presents pre-existing filter types that are already defined by HBase. Select the type of the filter you need to use. Filter column: enter the column qualifier on which you need to apply the active filter. This parameter becomes mandatory depending on the type of the filter and of the comparator you are using. For example, it is not used by the Row Filter type but is required by the Single Column Value Filter type. Filter family: enter the column family on which you need to apply the active filter. This parameter becomes mandatory depending on the type of the filter and of the comparator you are using. For example, it is not used by the Row Filter type but is required by the Single Column Value Filter type. Filter operation: select from the drop-down list the operation to be used for the active filter. Filter Value: enter the value on which you want to use the operator selected from the Filter operation drop-down list. Filter comparator type: select the type of the comparator to be combined with the filter you are using. Depending on the Filter type you are using, some or each of the parameters become mandatory. For further information, see HBase filters

Global Variables

Global Variables	NB_LINE: the number of rows read by an input component or transferred to an output component. This is an After variable and it returns an integer. 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 more information about variables, see Using contexts and variables.

NB_LINE: the number of rows read by an input component or transferred to an output component. This is an After variable and it returns an integer.

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 more information about variables, see Using contexts and variables.

Usage

Usage rule	This component is a start component of a Job and always needs an output link.
Prerequisites	Before starting, ensure that you have met the Loopback IP prerequisites expected by your database. 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 Talend 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\ hadoop\hadoop-VERSION\lib\native. For example, the library for Windows is \lib\native\MapRClient.dll in the MapR client jar file. 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 Talend 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 Talend 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.

Usage rule

This component is a start component of a Job and always needs an output link.

Prerequisites

Before starting, ensure that you have met the Loopback IP prerequisites expected by your database.

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 Talend 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\ hadoop\hadoop-VERSION\lib\native. For example, the library for Windows is \lib\native\MapRClient.dll in the MapR client jar file.

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 Talend 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 Talend 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.

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