[HBASE-21154] Remove hbase:namespace table; fold it into hbase:meta - ASF JIRA

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Details

Type: Improvement
Status: Resolved
Priority: Major
Resolution: Fixed
Affects Version/s: None
Fix Version/s: 3.0.0-alpha-1
Component/s: meta
Labels:
None

Hadoop Flags:

Incompatible change, Reviewed
Release Note:

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Add a new family called 'ns' for meta table and store the namespace related information in it instead of in namespace table. When rolling upgrading from a version which has namespace table, we will automatically migrate the data in namespace table to the 'ns' family of meta table, and then disable the namespace table. You can delete the namespace table later via the Admin interface.
The ZKNamespaceManager is also removed, as we never use its pub/sub ability in HBase.

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Add a new family called 'ns' for meta table and store the namespace related information in it instead of in namespace table. When rolling upgrading from a version which has namespace table, we will automatically migrate the data in namespace table to the 'ns' family of meta table, and then disable the namespace table. You can delete the namespace table later via the Admin interface. The ZKNamespaceManager is also removed, as we never use its pub/sub ability in HBase.

Description

Namespace table is a small system table. Usually it has two rows. It must be assigned before user tables but after hbase:meta goes out. Its presence complicates our startup and is a constant source of grief when for whatever reason, it is not up and available. In fact, master startup is predicated on hbase:namespace being assigned and will not make progress unless it is up.

Lets just add a new 'ns' column family to hbase:meta for namespace.

Here is a default ns table content:

hbase(main):023:0* scan 'hbase:namespace'
ROW                                                                                                      COLUMN+CELL
 default                                                                                                 column=info:d, timestamp=1526694059106, value=\x0A\x07default
 hbase                                                                                                   column=info:d, timestamp=1526694059461, value=\x0A\x05hbase