[ACCUMULO-1801] Create a SelectColumnsIterator

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: client
• Assignee: Christopher Tubbs
• Reporter: Mike Drob
• Created: 22/Oct/13 15:33
• Updated: 11/Jun/19 06:06

Description

A user can already limit columns on a scanner, however there is not an easy way to limit the columns propagated in the middle of an iterator stack. For example, if a user has data like the following:

user-1 age:25
user-1 occupation:Student
user-2 age:45
user-2 occupation:Engineer

and wants to get only the users that are younger than 30, it is easy to write a custom RowFilter to do that.

However, to get only the occupation of users under 30, there would need to be additional filtering done on the client side. If the rows get large or particularly numerous, then this becomes undesirable. And setting the fetch columns is not an option since that would hide the age column from the RowFilter.

Issue Links

• is depended upon by: ACCUMULO-3906 Drop the ability to filter column qualifiers natively in the scanner
• is depended upon by: ACCUMULO-4137 Deprecate fetchColumns which accepts column qualifiers