# Detecting and processing compressed files with Amazon EMR
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Hadoop checks the file extension to detect compressed files. The compression types supported by Hadoop are: gzip, bzip2, and LZO. You do not need to take any additional action to extract files using these types of compression; Hadoop handles it for you.

To index LZO files, you can use the hadoop-lzo library which can be downloaded from [https://github.com/kevinweil/hadoop-lzo](https://github.com/kevinweil/hadoop-lzo). Note that because this is a third-party library, Amazon EMR does not offer developer support on how to use this tool. For usage information, see [the hadoop-lzo readme file.](https://github.com/kevinweil/hadoop-lzo/blob/master/README.md)