tAvroOutput properties for Apache Spark Batch

Avro

author
Talend Documentation Team
EnrichVersion
6.4
EnrichProdName
Talend Data Fabric
Talend Big Data Platform
Talend Big Data
Talend Real-Time Big Data Platform
task
Design and Development > Third-party systems > File components (Integration) > Avro components
Data Governance > Third-party systems > File components (Integration) > Avro components
Data Quality and Preparation > Third-party systems > File components (Integration) > Avro components
EnrichPlatform
Talend Studio

These properties are used to configure tAvroOutput running in the Spark Batch Job framework.

The Spark Batch tAvroOutput component belongs to the File family.

The component in this framework is available only if you have subscribed to one of the Talend solutions with Big Data.

Basic settings

Define a storage configuration component

Select the configuration component to be used to provide the configuration information for the connection to the target file system such as HDFS.

If you leave this check box clear, the target file system is the local system.

The configuration component to be used must be present in the same Job. For example, if you have dropped a tHDFSConfiguration component in the Job, you can select it to write the result in a given HDFS system.

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.

The fields that come after are pre-filled in using the fetched data.

For further information about the Hadoop Cluster node, see the Getting Started Guide.

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.

Folder

Browse to, or enter the path pointing to the data to be used in the file system.

This path must point to a folder rather than a file, because a Talend Map/Reduce Job need to write in its target folder not only the final result but also multiple part- files generated in performing Map/Reduce computations.

The button for browsing does not work with the Spark Local mode; if you are using the Spark Yarn or the Spark Standalone mode, ensure that you have properly configured the connection in a configuration component in the same Job, such as tHDFSConfiguration.

Action

Select an operation for writing data:

Create: Creates a file and write data in it.

Overwrite: Overwrites the file existing in the directory specified in the Folder field.

Compression

Select the Compress data blocks check box to compress the output data.

Hadoop provides different compression formats that help reduce the space needed for storing files and speed up data transfer. When reading a compressed file, the Studio needs to uncompress it before being able to feed it to the input flow.

Advanced settings

Use output schema compatible with AvroKeyValueOutputFormat

Select this check box to define a hierarchical key/value schema for the Avro file to be written. According to this schema, the current component embeds the columns of the input row into an output record with two fields, named key and value.

For this purpose, you need to specify the columns of the output data to be used as key fields in the table that is displayed.

For example, the following data is an Avro record written with this key/value structure:
{ 
  "key" : { "key1" : 1,  "key2" :  "Canada"},
   "value" : { "value1" :  "maple syrup",  "value2" : 2015}
}

Usage

Usage rule

This component is used as an end component and requires an input link.

This component, along with the Spark Batch component Palette it belongs to, appears only when you are creating a Spark Batch Job.

Note that in this documentation, unless otherwise explicitly stated, a scenario presents only Standard Jobs, that is to say traditional Talend data integration Jobs.

Spark Connection

You need to use the Spark Configuration tab in the Run view to define the connection to a given Spark cluster for the whole Job. In addition, since the Job expects its dependent jar files for execution, you must specify the directory in the file system to which these jar files are transferred so that Spark can access these files:
  • Yarn mode: when using Google Dataproc, specify a bucket in the Google Storage staging bucket field in the Spark configuration tab; when using other distributions, use a tHDFSConfiguration component to specify the directory.

  • Standalone mode: you need to choose the configuration component depending on the file system you are using, such as tHDFSConfiguration or tS3Configuration.

This connection is effective on a per-Job basis.