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From "John Vines (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3918) Different locality groups can compact with different iterator stacks
Date Thu, 25 Jun 2015 17:39:04 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14601608#comment-14601608
] 

John Vines commented on ACCUMULO-3918:
--------------------------------------

Well, once you have a consistent iterator stack for the whole file, you can log the iterator
stack for the file (which would be follow on work). This would describe what iterator settings
were in place when the file compacted.

This is not the same as sequential compactions of different files because files are apparent
to users. It's how users think about the data on disk. They would track that a major compaction
happened and it outputted a file. I wouldn't expect the iterator stack to allow changes midway
through a scan, why would I design things to change midway through a compaction.

And telling people to offline their tables is horrible advise. That's a issue we should strengthen,
not tell people to suffer through.

> Different locality groups can compact with different iterator stacks
> --------------------------------------------------------------------
>
>                 Key: ACCUMULO-3918
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3918
>             Project: Accumulo
>          Issue Type: Bug
>          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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