Daniel Vimont created HBASE-17257:
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Summary: Add column-aliasing capability to hbase-client
Key: HBASE-17257
URL: https://issues.apache.org/jira/browse/HBASE-17257
Project: HBase
Issue Type: New Feature
Components: Client
Affects Versions: 2.0.0
Reporter: Daniel Vimont
Assignee: Daniel Vimont
Column aliasing will provide the option for a 1, 2, or 4 byte alias value to be
stored in each cell of an "alias enabled" column-family, in place of the
full-length column-qualifier. Aliasing is intended to operate completely
invisibly to the end-user developer, with absolutely no "awareness" of aliasing
required to be coded into a front-end application. No new public hbase-client
interfaces are to be introduced, and only a few new public methods should need
to be added to existing interfaces, primarily to allow an administrator to
designate that a new column-family is to be alias-enabled by setting its
aliasSize attribute to 1, 2, or 4.
To facilitate such functionality, new subclasses of HTable,
BufferedMutatorImpl, and HTableMultiplexer are to be provided. The overriding
methods of these new subclasses will invoke methods of the new AliasManager
class to facilitate qualifier-to-alias conversions (for user-submitted Gets,
Scans, and Mutations) and alias-to-qualifier conversions (for Results returned
from HBase) for any Table that has one or more alias-enabled column families.
All conversion logic will be encapsulated in the new AliasManager class, and
all qualifier-to-alias mappings will be persisted in a new aliasMappingTable in
a new, reserved namespace.
An informal polling of HBase users at HBaseCon East and at the
Strata/Hadoop-World conference in Sept. 2016 showed that Column Aliasing could
be a popular enhancement to standard HBase functionality, due to the fact that
full column-qualifiers are stored in each cell, and reducing this qualifier
storage requirement down to 1, 2, or 4 bytes per cell could prove beneficial in
terms of reduced storage and bandwidth needs. Aliasing is intended chiefly for
column-families which are of the "narrow and tall" variety (i.e., that are
designed to use relatively few distinct column-qualifiers throughout a large
number of rows, throughout the lifespan of the column-family). A column-family
that is set up with an alias-size of 1 byte can contain up to 255 unique
column-qualifiers; a 2 byte alias-size allows for up to 65,535 unique
column-qualifiers; and a 4 byte alias-size allows for up to 4,294,967,295
unique column-qualifiers.
Fuller specifications will be entered into the comments section below. Note
that it may well not be viable to add aliasing support in the new "async"
classes that appear to be currently under development.
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