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https://issues.apache.org/jira/browse/ASTERIXDB-1556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15499768#comment-15499768
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Taewoo Kim commented on ASTERIXDB-1556:
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@[~buyingyi]: If we assume that each field consists of at least 4 bytes, that
means there are 32 bits. The max value of INT is 2^31 -1, which is greater than
32MB (2^25), 64MB (2^26), or 128MB (2^27). What I'm trying to say here is that
for a reasonable budget size, we always choose the number of possible tuples in
data table rather than considering both (# of tuples, # of hash entries). I
think the formula might be reduced to y = 32M / (8+4+1) * 40 to calculate the
expected byte size of hash table. Then y / (32 + y) to get the actual ratio.
How's your thought?
> 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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