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From "Sergey Shelukhin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-16151) BytesBytesHashTable allocates large arrays
Date Tue, 14 Mar 2017 00:25:41 GMT

    [ https://issues.apache.org/jira/browse/HIVE-16151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15923302#comment-15923302
] 

Sergey Shelukhin commented on HIVE-16151:
-----------------------------------------

[~gopalv] can you review this at some point? thanks
[~mmccline] mentioned that you may not like this approach ;)

> BytesBytesHashTable allocates large arrays
> ------------------------------------------
>
>                 Key: HIVE-16151
>                 URL: https://issues.apache.org/jira/browse/HIVE-16151
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Prasanth Jayachandran
>            Assignee: Sergey Shelukhin
>         Attachments: HIVE-16151.patch
>
>
> These arrays cause GC pressure and also impose key count limitations on the table. Wrt
the latter, we won't be able to get rid of it without a 64-bit hash function, but for now
we can get rid of the former. If we need the latter we'd add murmur64 and probably account
for it differently for resize (we don't want to blow up the hashtable by 4 bytes/key in the
common case where #of keys is less than ~1.5B :))



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