Delete columns by prefix

[Jan Lukavský <je...@seznam.cz>]

Hi all,

I have come across a rather old issue 
https://issues.apache.org/jira/browse/HBASE-5268, which is marked as 
Won't fix and I would like to open a discussion about the topic 
described. I understand the difficulties that the full implementation 
brings to the get/scan process, but I think that the use-case described 
in the JIRA might be beneficial to a lot of use-cases. My question is, 
whether the problem of retrieving the deletion marker for a prefix of a 
qualifier could be solved by introducing some structure to the qualifier 
itself. Let me elaborate on this:

  - suppose we give qualified a structure, say in a form of 
`<prefix>.<suffix>`, with a fixed delimiter character (.)

  - delete operation would be allowed only on the <suffix> part, and 
will therefore be written as a "delete prefix" marker on qualifier 
`<prefix>.`

  - a get operation on a qualifier containing the delimiter character 
(might be configurable), would then have to fetch only the row start (to 
be able to determine whether the row as a whole was not deleted) and 
then delete marker for the qualifier `<prefix>.`

I think this implementation would not suffer from the issues described 
in the original JIRA and would be still practically usable for users, 
while being a lot more efficient then what listing all the qualifiers 
being actually written and deleting then one by one.

Thanks for any comments or insights.

Best,

  Jan