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From "Christopher Tubbs (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-571) Merge table into existing table
Date Wed, 15 Oct 2014 19:11:33 GMT


Christopher Tubbs commented on ACCUMULO-571:

Two things:

# this implementation might be easier with ACCUMULO-3235 (although it could do chops in the
# a good name for this in the API, depending on actual behavior, might be "union", because
it seems very analogous to SQL unions of tables (or views; the range subset is a view)

> Merge table into existing table
> -------------------------------
>                 Key: ACCUMULO-571
>                 URL:
>             Project: Accumulo
>          Issue Type: New Feature
>          Components: client, tserver
>            Reporter: John Vines
>            Assignee: John Vines
>              Labels: gsoc2013, mentor
>             Fix For: 1.7.0
> This is idea that was recently brought to my attention. The use case is a user wants
to essentially clone a subset of a table into an existing table. Currently cloning does not
allow this. Current option is to copy the files in hdfs and then bulk import, since bulk import
moves the files. This is pretty wasteful. Under the hood, the system can handle the cross-linking
between files like that. We just need a mechanism to provide the ability to assign a subset
of data to another region.
> Potential uses include the above mentioned, as well as the potential for users to bring
fresh data into a table which was cloned and modified. There may be other cases, but I haven't
fully thought out this problem space.
> The biggest problem with this is it does put the onus on the user for ensuring that data
in the in memory maps is flushed before moving, as well as for handling the possibility of
duplicate data.

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