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Is the Hbase's Write Ahead Log (WAL) immutable  ?

Question asked by Wibe2017 on Nov 29, 2017
Latest reply on Nov 30, 2017 by cathy



I am learning about Hbase architecture, and I came accross the components of a Region Server, 


As I understand, the WAL is an HDFS file that is used to log all the incoming edits in a sequence in order to be able to recover data in case of failure. But I am intrigged by the fact that I know that HDFS files are immutable.


So how can the WAL still be modified by each incoming edit from Hbase clients, while at the same time it is an immutable file?  


Many thanks