[ACCUMULO-906] Combiners documention could be improved

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.4.0, 1.4.1, 1.4.2
• Fix Version/s: 1.4.3, 1.5.0
• Assignee: Eric C. Newton
• Reporter: Eric C. Newton
• Created: 14/Dec/12 15:36
• Updated: 19/Dec/12 18:15
• Resolved: 19/Dec/12 17:21

Description

Goal: sum all the values across all columns.

> createtable animal
> deleteiter -n vers -scan -minc -majc
> setiter -t animal -p 10 -scan -n sum -class org.apache.accumulo.core.iterators.user.SummingCombiner
SummingCombiner interprets Values as Longs and adds them together.  A variety of encodings (variable length, fixed length, or string) are available
----------> set SummingCombiner parameter all, set to true to apply Combiner to every column, otherwise leave blank. if true, columns option will be ignored.: true
----------> set SummingCombiner parameter columns, <col fam>[:<col qual>]{,<col fam>[:<col qual>]} escape non-alphanum chars using %<hex>.: 
----------> set SummingCombiner parameter lossy, if true, failed decodes are ignored. Otherwise combiner will error on failed decodes (default false): <TRUE|FALSE>: 
----------> set SummingCombiner parameter type, <VARLEN|FIXEDLEN|STRING|fullClassName>: STRING
> insert mammal cow ellie 1
> insert mammal cow nell  1
> insert mammal man eric  1
> scan
expected: mammal dontcare : dontcare 3

Where "dontcare" can come back with anything; I just don't care.
But I just get this

mammal cow:ellie []    1
mammal cow:nell []    1
mammal man:eric []    1

I can't get the combiner to come back with a sum of mammals or cows.