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From "Lars George (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-18388) Fix description on region page, explaining what a region name is made of
Date Sun, 16 Jul 2017 18:31:01 GMT
Lars George created HBASE-18388:
-----------------------------------

             Summary: Fix description on region page, explaining what a region name is made
of
                 Key: HBASE-18388
                 URL: https://issues.apache.org/jira/browse/HBASE-18388
             Project: HBase
          Issue Type: Improvement
          Components: master, regionserver, UI
    Affects Versions: 2.0.0-alpha-1, 1.3.1
            Reporter: Lars George
            Priority: Minor


In the {{RegionListTmpl.jamon}} we have this:

{code}
    <p>Region names are made of the containing table's name, a comma,
    the start key, a comma, and a randomly generated region id.  To illustrate,
    the region named
    <em>domains,apache.org,5464829424211263407</em> is party to the table
    <em>domains</em>, has an id of <em>5464829424211263407</em> and
the first key
    in the region is <em>apache.org</em>.    The <em>hbase:meta</em>
'table' is an internal
    system table (or a 'catalog' table in db-speak).
    The hbase:meta table keeps a list of all regions in the system. The empty key is used
to denote
    table start and table end.  A region with an empty start key is the first region in a
table.
    If a region has both an empty start key and an empty end key, it's the only region in
the
    table. See <a href="http://hbase.org">HBase Home</a> for further explication.<p>
{code}

This is wrong and worded oddly. What needs to be fixed facts wise is:

- Region names contain (separated by commas) the full table name (including the namespace),
the start key, the time the region was created, and finally a dot with an MD5 hash of everything
before the dot. For example: {{test,,1499410125885.1544f69aeaf787755caa11d3567a9621.}}
- The trailing dot is to distinguish legacy region names (like those used by the {{hbase:meta}}
table)
- The MD5 hash is used as the directory name within the HBase storage directories
- The names for the meta table use a Jenkins hash instead, also leaving out the trailing dot,
for example {{hbase:meta,,1.1588230740}}. The time is always set to {{1}}.
- The start key is printed in safe characters, escaping unprintable characters
- The link to the HBase home page to explain more is useless and should be removed.
- Also, for region replicas, the replica ID is inserted into the name, like so {{replicatable,,1486289678486_0001.3e8b7655299b21b3038ff8d39062467f.}},
see the {{_0001}} part.

As for the wording, I would just make this all flow a little better, that "is party of" sounds
weird to me (IMHO).



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