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From "Taewoo Kim (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ASTERIXDB-1556) Hash Table used by External hash group-by doesn't conform to the budget.
Date Tue, 01 Nov 2016 20:46:58 GMT

    [ https://issues.apache.org/jira/browse/ASTERIXDB-1556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15626626#comment-15626626
] 

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

Talked with [~chenli@gmail.com]: since Hash Table and Data Table are managed differently (Hash
Table: own management, Data Table: VPartitionTupleBufferManager), the sum of H and D may be
greater than M, but we may not get any space back even if we deallocate frames in the buffer
manager and compact hash table. So, a solution is let Hash Table and Data Table be controlled
by the same buffer manager. 

> 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
>            Priority: Critical
>              Labels: soon
>         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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