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From "Eric Newton (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-1218) document the recovery from a failed zookeeper
Date Tue, 25 Mar 2014 14:19:14 GMT


Eric Newton commented on ACCUMULO-1218:

[~elserj] you can also get data back that had been compacted out.

Let's say we have a table in a single tablet that contains rows [a, b, d... x, y, z].  The
tablet splits to (-inf, m] and (m, +inf).  Both tablets use the file that contains [a...z].

Now I delete row a with a bunch of delete markers.  The table contains [b, c, ... z].

I compact (-inf, m].  So I have [b...m] and [n...z] in separate tablets.  But remember, row
a still lives in a file pointed to by (m, +inf).

If zookeeper dies, and I re-import files.  Row a will return.

> document the recovery from a failed zookeeper
> ---------------------------------------------
>                 Key: ACCUMULO-1218
>                 URL:
>             Project: Accumulo
>          Issue Type: Sub-task
>          Components: docs
>            Reporter: Eric Newton
>            Assignee: Josh Elser
>              Labels: Documentation
>             Fix For: 1.6.0
>         Attachments: 0001-ACCUMULO-1218-Overview-on-how-to-recover-an-instance.patch
> Document bulk-import based recovery of accumulo.
> Include a stern warning and possible data loss and unwanted data recovery.

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