Author: mdrob
Date: Wed Apr 23 15:59:02 2014
New Revision: 1589445
URL: http://svn.apache.org/r1589445
Log:
CMS commit to accumulo by mdrob
Modified:
accumulo/site/trunk/content/glossary.mdtext
Modified: accumulo/site/trunk/content/glossary.mdtext
URL:
http://svn.apache.org/viewvc/accumulo/site/trunk/content/glossary.mdtext?rev=1589445&r1=1589444&r2=1589445&view=diff
==============================================================================
--- accumulo/site/trunk/content/glossary.mdtext (original)
+++ accumulo/site/trunk/content/glossary.mdtext Wed Apr 23 15:59:02 2014
@@ -25,7 +25,7 @@ Notice: Licensed to the Apache Softwa
- **iterator** - a mechanism for modifying tablet-local portions of the
key/value space. Iterators are used for standard administrative tasks as well
as for custom processing.
- **iterator priority** - an iterator must be configured with a particular
scope and priority. When a tablet server enters that scope, it will
instantiate iterators in priority order starting from the smallest priority and
ending with the largest, and apply each to the data read before rewriting the
data or sending the data to the user.
- **iterator scopes** - the possible scopes for iterators are where the tablet
server is already reading and/or writing data: minor compaction / flush time
(*minc* scope), major compaction / file merging time (*majc* scope), and query
time (*scan* scope)
-- **gc** - process that identifies temporary files that are no longer needed
by any process, and deletes them.
+- **gc** - process that identifies temporary files in HDFS that are no longer
needed by any process, and deletes them.
- **key** - the key into the distributed sorted map which is accumulo. The
key is subdivided into row, column, and timestamp. The column is further
divided into family, qualifier, and visibility.
- **locality group** - a set of column families that will be grouped together
on disk. With no locality groups configured, data is stored on disk in row
order. If each column family were configured to be its own locality group, the
data for each column would be stored separately, in row order. Configuring
sets of columns into locality groups is a compromise between the two approaches
and will improve performance when multiple columns are accessed in the same
scan.
- **log-structured merge-tree** - the sorting / flushing / merging scheme on
which BigTable's design is based.
