apurtell opened a new pull request #3244: URL: https://github.com/apache/hbase/pull/3244
WAL storage can be expensive, especially if the cell values represented in the edits are large, consisting of blobs or significant lengths of text. Such WALs might need to be kept around for a fairly long time to satisfy replication constraints on a space limited (or space-contended) filesystem. We have a custom dictionary compression scheme for cell metadata that is engaged when WAL compression is enabled in site configuration. This is fine for that application, where we can expect the universe of values and their lengths in the custom dictionaries to be constrained. For arbitrary cell values it is better to use Deflate compression, which is which is a complete LZ-class algorithm suitable for arbitrary albeit compressible data, is reasonably fast, certainly fast enough for WALs, compresses well, and is universally available as part of the Java runtime. With a trick that encodes whether or not the cell value is compressed in the high order bit of the type byte, this can be done in a backwards compatible manner. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
