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Date: Thu, 11 Aug 2016 21:59:20 +0000 (UTC)
From: "Taewoo Kim (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (ASTERIXDB-1556) Hash Table used by External
 hash group-by doesn't conform to the budget.
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archived-at: Thu, 11 Aug 2016 21:59:25 -0000


    [ https://issues.apache.org/jira/browse/ASTERIXDB-1556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15418007#comment-15418007 ] 

Taewoo Kim commented on ASTERIXDB-1556:
---------------------------------------

I see. We can keep the current scheme (just setting the number of used slot as zero for the hash values that are corresponding to those of the spilled data parition) and just coalescing hash slots (remove dead spaces). 

> Hash Table used by External hash group-by doesn't conform to the budget.
> ------------------------------------------------------------------------
>
>                 Key: ASTERIXDB-1556
>                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-1556
>             Project: Apache AsterixDB
>          Issue Type: Bug
>            Reporter: Taewoo Kim
>            Assignee: Taewoo Kim
>         Attachments: 2wayjoin.pdf, 2wayjoin.rtf, 2wayjoinplan.rtf, 3wayjoin.pdf, 3wayjoin.rtf, 3wayjoinplan.rtf
>
>
> When we enable prefix-based fuzzy-join and apply the multi-way fuzzy-join ( > 2), the system generates an out-of-memory exception. 
> Since a fuzzy-join is created using 30-40 lines of AQL codes and this AQL is translated into massive number of operators (more than 200 operators in the plan for a 3-way fuzzy join), it could generate out-of-memory exception.
> /// Update: as the discussion goes, we found that hash table in the external hash group by doesn't conform to the frame limit. So, an out of memory exception happens during the execution of an external hash group by operator.


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