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https://issues.apache.org/jira/browse/IMPALA-2281?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tianyi Wang resolved IMPALA-2281.
---------------------------------
Resolution: Fixed
Fix Version/s: Impala 2.11.0
IMPALA-2281: Replace FNV with FastHash in exchange nodes
FNV is not a good enough hash function. This patch introduces FastHash
into the codebase and uses it in exchange nodes.
Testing: Two test cases involving arbitrary ordering are changed.
Single node performance benchmark shows no performance difference.
Change-Id: I778317d982dcdb94173a369a65b39f32b4f7ded2
Reviewed-on: http://gerrit.cloudera.org:8080/8417
Reviewed-by: Jim Apple <[email protected]>
Tested-by: Impala Public Jenkins
> Use a better hash function than FNV for exchanges
> -------------------------------------------------
>
> Key: IMPALA-2281
> URL: https://issues.apache.org/jira/browse/IMPALA-2281
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Affects Versions: Impala 2.2
> Reporter: Tim Armstrong
> Assignee: Tianyi Wang
> Priority: Minor
> Fix For: Impala 2.11.0
>
> Attachments: performance_result.txt
>
>
> The FNV hash function is used in Impala to hash data for exchanges and there
> are various utility functions for computing FNV hashes of different data
> types. There are clearly superior alternatives. For example, Murmur2 is
> already in the codebase, is faster to compute, and has better distribution
> properties.
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