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Snap type:

Write

Description:

This Snap converts documents into the ORC format and writes the data to HDFS, S3, or the local file system.

  • Expected upstream Snaps: Any Snap with a document output view.
  • Expected downstream Snaps: [None]
  • Expected input: A document.
  • Expected output: [None]
Prerequisites:

[None]

Support and limitations:
Note

All expression Snap properties (when '=' button is pressed) can be evaluated from pipeline parameters only, not from input documents. Input documents are data to be formatted and written to the target files.


Account: 

The ORC Writer works with the following accounts:

Views:


InputThis Snap has exactly one document input view. 
Output

This Snap has at most one document output view.

ErrorThis Snap has at most one document error view and produces zero or more documents in the view.


Settings

Label

Required. The name for the Snap. You can modify this to be more specific, especially if you have more than one of the same Snap in your pipeline.

Default Value: ORC Writer

Directory



Required. The path to a directory from which you want the ORC Reader Snap to read data. All files within the directory must be ORC formatted.

Basic directory URI structure

  • HDFS: hdfs://<hostname>:<port>/
  • S3: s3:///<S3 bucket name>/<file-path>
  • ABFS(S): abfs(s):///filesystem/<path>/
  • ABFS(S): abfs(s)://filesystem@accountname.endpoint/<path>

The Directory property is not used in the pipeline execution or preview, and used only in the Suggest operation. When you press the Suggest icon, the Snap displays a list of subdirectories under the given directory. It generates the list by applying the value of the Filter property.

Example

  • hdfs://ec2-54-198-212-134.compute-1.amazonaws.com:8020/user/john/input/

  • webhdfs://cdh-qa-2.fullsail.Snaplogic.com:50070/user/ec2-user/csv/
  • s3://test-s3-drea/8867_output.json
  • _dirname 

  • file:///home/snaplogic/file.orc
  • abfs:///filesystem2/dir1
  • abfs://filesystem2@snaplogicaccount.dfs.core.windows.net/dir1

Default valuehdfs://<hostname>:<port>/


Filter


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HDFS Writer
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File




Required for standard mode. Filename or a relative path to a file under the directory given in the Directory property. It should not start with a URL separator "/". The File property can be a JavaScript expression which will be evaluated with values from the input view document. When you press the Suggest icon, it will display a list of regular files under the directory in the Directory property. It generates the list by applying the value of the Filter property.

Use Hive tables if your input documents contains complex data types, such as maps and arrays.

Example: 

  • sample.orc
  • tmp/another.orc
  • _filename

Default value:  [None]

File action


Required. Select an action to take when the specified file already exists in the directory. Please note the Append file action is supported for SFTP, FTP, and FTPS protocols only.

Default value: [None]

File permissions for various users

Set the user and desired permissions.

Default value: [None]

Hive Metastore URL


This setting is used to assist in setting the schema along with the database and table setting.  If the data being written has a Hive schema, then the Snap can be configured to read the schema instead of manually entering it. Set the value to a Hive Metastore URL where the schema is defined.

Default value: [None]

Database

The Hive Metastore database where the schema is defined. See the Hive Metastore URL setting for more information.

Table

The table from which the schema in the Hive Metastore's database must be read. See the Hive Metastore URL setting for more information.

Compression

Required. The compression type to be used when writing the file. 

Column paths


Paths where the column values appear in the document. This property is required if the Hive Metastore URL property is empty.

Examples:

  • Column Name: Fun
  • Column Path: $column_from_input_data
  • Column Type: string

Default value: [None]

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Troubleshooting

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Examples

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titleORC Writer Writing to an HDFS Instance

ORC Writer Writing to an HDFS Instance

Here is an example of a ORC Writer configured to write to a local instance of HDFS. The output is written to /tmp/orc-output. The Hive Metastore used reads the schema from the employee_orc table from the masterdb database. No column paths or compression are used. For an example of the Schema, see the documentation on the Schema setting.


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