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https://issues.apache.org/jira/browse/BEAM-10824?focusedWorklogId=478914&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-478914
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ASF GitHub Bot logged work on BEAM-10824:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 04/Sep/20 03:05
Start Date: 04/Sep/20 03:05
Worklog Time Spent: 10m
Work Description: monicadsong commented on pull request #12756:
URL: https://github.com/apache/beam/pull/12756#issuecomment-686873008
Benchmark on 3B dataset showed accurate results. And modified the unit test
to confirm the expected error-- the error for this algorithm is an expected
error, not a max error, so certain inputs will exceed the expected error.
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Issue Time Tracking
-------------------
Worklog Id: (was: 478914)
Remaining Estimate: 16h 10m (was: 16h 20m)
Time Spent: 7h 50m (was: 7h 40m)
> Hash in stats.ApproximateUniqueCombineFn NON-deterministic
> ----------------------------------------------------------
>
> Key: BEAM-10824
> URL: https://issues.apache.org/jira/browse/BEAM-10824
> Project: Beam
> Issue Type: Bug
> Components: sdk-py-core
> Reporter: Monica Song
> Priority: P1
> Labels: hash
> Original Estimate: 24h
> Time Spent: 7h 50m
> Remaining Estimate: 16h 10m
>
> The python hash() function is non-deterministic. As a result, different
> workers will map identical values to different hashes. This leads to
> overestimation of the number of unique values (by several magnitudes, in my
> experience x1000) in a distributed processing model.
> [https://github.com/apache/beam/blob/master/sdks/python/apache_beam/transforms/stats.py#L218]
>
>
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