Revision 1304626

[jira] [HBASE-5469] Add baseline compression efficiency to DataBlockEncodingTool

Summary:
DataBlockEncodingTool currently does not provide baseline compression
efficiency, e.g. Hadoop compression codec applied to unencoded data. E.g. if
we are using LZO to compress blocks, we would like to have the following
columns in the report (possibly as percentages of raw data size).

Baseline K+V in blockcache | Baseline K + V on disk (LZO compressed) | K + V
DataBlockEncoded in block cache | K + V DataBlockEncoded + LZOCompressed (on
disk)

Background: we never store compressed blocks in cache, but we always store
encoded data blocks in cache if data block encoding is enabled for the column
family.

This patch also has multiple bugfixes and improvements to DataBlockEncodingTool,
including presentation format, memory requirements (reduced 3x) and fixing the
handling of compression.

Test Plan:
* Run unit tests.
* Run DataBlockEncodingTool on a variety of real-world HFiles.

Reviewers: JIRA, dhruba, tedyu, stack, heyongqiang

Reviewed By: tedyu

Differential Revision: https://reviews.facebook.net/D2409