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From "Keith Turner (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-3236) Clone table into an existing table
Date Mon, 20 Oct 2014 14:06:34 GMT


Keith Turner commented on ACCUMULO-3236:

On Fri, Oct 17, 2014 at 11:05 AM, Sean Busbey (JIRA) <>

Strictly speaking, Accumlo does not have snapshots.  A user can clone A to
B, write to B, and then offline B.  Since data was written to B, its not a
snapshot of A.  Accumulo does nothing to prevent these writes, so a user
can never be 100% certain they have a pristine snapshot.   Also you can
never be sure that another user did not bring a clone online, write to it,
and take it offline.  I think for Accumulo to have snapshots, we would need
a new SNAPSHOT table state.  When in this state, can only read the table
and can only transition to the DELETING table state.  Also, would start in
the SNAPSHOT state.

> Clone table into an existing table
> ----------------------------------
>                 Key: ACCUMULO-3236
>                 URL:
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: client, tserver
>            Reporter: John Vines
>             Fix For: 1.7.0
> Currently we have the ability to clone a table, which takes all files belonging to an
existing table and then makes them owned by a second, brand new table. I think there is a
logic extension to this where you can add the files to an already existing table.
> One point of concern is if data is unused in existing files due to major compactions
of the shared files in the source table. This can be mitigated by either chopping the files
(which sorta goes against the idea of cloning) or ensuring that at source table splits exist
in the destination table.

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