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From "Billie Rinaldi (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-461) Provide convenient mechanism for checking constraints client side
Date Thu, 10 May 2012 20:30:50 GMT


Billie Rinaldi commented on ACCUMULO-461:

This is harder than it sounds.  I have evaluated AccumuloOutputFormat and AccumuloFileOutputFormat
for constraint checking.  The main issue is that the check method of Constraint takes an Environment
(consisting of an extent, a user name, and authorizations) and a Mutation.  Adding client-side
constraint checking into AccumuloOutputFormat wouldn't be too difficult, as much of this information
(except the extent) is already required by the format.  However, constraints are already being
checked on the server side, so the effect is not huge -- it would just result in an error
being thrown a bit earlier.  Where constraint checking could be really useful is in the AccumuloFileOutputFormat.
 This format does not provide any user or authorizations information, so it would have to
be added in, as well as information needed to read the constraints for a particular table
or a fixed list of constraints to check.  Also, this output format writes keys and values,
so these would have to be grouped together into mutations for the check (taking into account
that some rows might be very large and could not be grouped into a single mutation).
> Provide convenient mechanism for checking constraints client side
> -----------------------------------------------------------------
>                 Key: ACCUMULO-461
>                 URL:
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: client
>            Reporter: John Vines
>            Assignee: Billie Rinaldi
>             Fix For: 1.5.0
> Currently constraints are run on the server side. If the user is running a map reduce
which is writing, they may want to make attempts to validate data before writing to make error
handling easier. We should provide a generic client mechanism to load a table's constraints
and check them before sending them to the batchwriter. 

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