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Ted Yu commented on HBASE-17257: -------------------------------- I think it is equally likely that alias table is unavailable whether the table is in hbase_alias_table or hbase namespace. Please put the patch on review board. > 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 > Labels: features > Attachments: HBASE-17257-v2.patch, HBASE-17257-v3.patch, > HBASE-17257.patch > > > 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)