-sum of mutation.numBytes() significantly different from rfile size
Slater, David M. 2013-10-29, 21:50
I'm seeing about an order of magnitude difference between the number of bytes returned by mutation.numBytes() and the size of the rfiles on disk (Accumulo 1.4.2). Note that all of my mutations are new entries, and there are no combiners running.
While I understand that there is some compression on the rfile, I would be really surprised if it was 10:1.
My entries are composed of a row ID (most of which is equivalent to the previous row ID), an empty column family, a nonempty column qualifier (which likely shares a lot with the previous qualifier), and an empty value. An example of the rowID and column qualifier might be:
<timeblock>|<hash>|<uid> <index>|<textual value>
The numBytes() method appears to return a number of bytes equal to the string length of the row ID and column qualifiers, plus 26 * # of column qualifiers.
Is there something else that I'm missing, or would this possibly compress by that much?