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https://issues.apache.org/jira/browse/ACCUMULO-461?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13272725#comment-13272725
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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: https://issues.apache.org/jira/browse/ACCUMULO-461
> 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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