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From "Keith Turner (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-1000) support compare and set
Date Wed, 05 Jun 2013 13:48:21 GMT


Keith Turner commented on ACCUMULO-1000:

I wrote a simple client side implementation of ConditionalWriter so I could start writing
unit test.  During this process I stumbled upon some things I had not considered in the design.
 Conceptually a conditional writer will read and write.  To read, it must use a set of auths.
 There are a few options :
 # User must pass a set of auths to conditional writer
 # User can not pass auths, Conditional writer uses all of users auths to read.
 # User can optionally pass auths, if they do not then use all of users auths
 # User can optionally pass auths, if they do not then use empty set of auths

I am leaning twoards #1 because its consistent w/ the scanner API.  #3 is like the scanner
API, but maybe more convenient.  #4 seems like it would cause problems.  I am thinking if
we decided to do something besides #1, that the Scanner API should be made consistent.   ACCUMULO-246
is also a consideration.

Another issue is that an absence test could pass when data is not really absent, its just
that user can not see it.  To remedy this I am thinking of making the absence condition fail
if the auths supplied are not sufficient to read the column.  This would not be a test against
data in Accumulo, only against the col vis supplied in the mutation condition.

One last thing, I am thinking of renaming putCondition() and putConditionAbsent() to putEqualityTest()
and putAbsenceTest().  

> support compare and set
> -----------------------
>                 Key: ACCUMULO-1000
>                 URL:
>             Project: Accumulo
>          Issue Type: New Feature
>          Components: client, tserver
>            Reporter: Keith Turner
>            Assignee: Keith Turner
>             Fix For: 1.6.0
>         Attachments: ACCUMULO-1000-proposal-01.html, ACCUMULO-1000-proposal-01.txt
> Add support to mutation for compare and set operations.  This would allow user to specify
that a row must contain certain data for a mutation to be applied.

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