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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2020/10/01 22:39:00 UTC
[jira] [Work logged] (HIVE-24221) Use vectorizable expression to
combine multiple columns in semijoin bloom filters
[ https://issues.apache.org/jira/browse/HIVE-24221?focusedWorklogId=493721&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-493721 ]
ASF GitHub Bot logged work on HIVE-24221:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 01/Oct/20 22:38
Start Date: 01/Oct/20 22:38
Worklog Time Spent: 10m
Work Description: zabetak opened a new pull request #1544:
URL: https://github.com/apache/hive/pull/1544
### What changes were proposed in this pull request?
Use hash(hash(hash(a,b),c),d) instead of hash(a,b,c,d) when constructing
the multi-col semijoin reducer.
### Why are the changes needed?
In order to use fully vectorized execution on multi-col semijoin reducers.
### Does this PR introduce _any_ user-facing change?
Only changes in EXPLAIN plans.
### How was this patch tested?
`mvn test -Dtest=TestTezPerfCliDriver -Dqfile="query50.q"`
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Issue Time Tracking
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Worklog Id: (was: 493721)
Remaining Estimate: 0h
Time Spent: 10m
> Use vectorizable expression to combine multiple columns in semijoin bloom filters
> ---------------------------------------------------------------------------------
>
> Key: HIVE-24221
> URL: https://issues.apache.org/jira/browse/HIVE-24221
> Project: Hive
> Issue Type: Improvement
> Components: Query Planning
> Environment:
> Reporter: Stamatis Zampetakis
> Assignee: Stamatis Zampetakis
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently, multi-column semijoin reducers use an n-ary call to GenericUDFMurmurHash to combine multiple values into one, which is used as an entry to the bloom filter. However, there are no vectorized operators that treat n-ary inputs. The same goes for the vectorized implementation of GenericUDFMurmurHash introduced in HIVE-23976.
> The goal of this issue is to choose an alternative way to combine multiple values into one to pass in the bloom filter comprising only vectorized operators.
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