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From "Keith Turner (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-3918) Different locality groups can compact with different iterator stacks
Date Thu, 25 Jun 2015 18:25:06 GMT


Keith Turner commented on ACCUMULO-3918:

I think taking a snapshot of the configuration at the beginning of compaction and using that
snapshot to construct all iterators used for the compaction would be a nice improvement. 
For the case of filtering rows it makes it easier to reason about which rows are filtered
in locality groups in rfiles. 

Not 100% sure, but I think trying to reusue the iterator stack would kinda ugly code wise.
  But maybe it could be done nicely.   I think using a snapshot of config would accomplish
the goal.  Couple compactions using a snapshot of config with ACCUMULO-1568 which makes config
updates atomic and that would be really nice.

[~vines] what do you think about making this an improvement instead of a bug?

> Different locality groups can compact with different iterator stacks
> --------------------------------------------------------------------
>                 Key: ACCUMULO-3918
>                 URL:
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: tserver
>    Affects Versions: 1.6.0
>            Reporter: John Vines
> While looking through the compactor code, I noticed that we load the iterator stack for
each locality group written and drop it when we're done. This means if a user reconfigures
iterators while a locality group is being written, the following locality groups will be compacted
inconsistently with the rest of the file.
> We should really read the stack once and be consistent for the entire file written.

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