---
title: Unloading Data from Greenplum Database 
---

A writable external table allows you to select rows from other database tables and output the rows to files, named pipes, to applications. You can define file-based and web-based writable external tables.

This topic describes how to unload data from Greenplum Database using parallel unload \(writable external tables\) and non-parallel unload \(`COPY`\).

-   **[Defining a File-Based Writable External Table](../../load/topics/g-defining-a-file-based-writable-external-table.html)**  

-   **[Defining a Command-Based Writable External Web Table](../../load/topics/g-defining-a-command-based-writable-external-web-table.html)**  

-   **[Unloading Data Using a Writable External Table](../../load/topics/g-unloading-data-using-a-writable-external-table.html)**  

-   **[Unloading Data Using COPY](../../load/topics/g-unloading-data-using-copy.html)**  

-   **[Unloading File Data Using Greenplum Streaming Server](../../load/topics/g-unloading-data-using-gpss.html)**


**Parent topic:** [Loading and Unloading Data](../../load/topics/g-loading-and-unloading-data.html)

