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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