Shulou(Shulou.com)05/31 Report--

This article mainly introduces what Sequencefile is, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

SequenceFile is a binary file provided by Hadoop API that serializes data into a file in the form of. The binaries are serialized and deserialized internally using Hadoop's standard Writable interface. It is compatible with MapFile in Hadoop API. SequenceFile in Hive inherits from Hadoop API's SequenceFile, but its key is empty and uses value to store the actual values in order to avoid the sorting process of MR during the map phase.

File structure diagram of SequenceFile:

Header common header file format:

SEQ3BYTENun1byte numeric keyClassNameValueClassNamecompression (boolean) indicates whether compression blockCompression (boolean, indicates whether it is block compression) compressioncodecMetadata file metadata Sync header file end flag is enabled in the file

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