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Posted to issues@beam.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2019/02/27 13:26:00 UTC
[jira] [Work logged] (BEAM-6670) Option to disable
reparallelization in JdbcIO.Read
[ https://issues.apache.org/jira/browse/BEAM-6670?focusedWorklogId=205145&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-205145 ]
ASF GitHub Bot logged work on BEAM-6670:
----------------------------------------
Author: ASF GitHub Bot
Created on: 27/Feb/19 13:25
Start Date: 27/Feb/19 13:25
Worklog Time Spent: 10m
Work Description: Noctune commented on pull request #7956: [BEAM-6670] Add option to disable reshuffling of JdbcIO
URL: https://github.com/apache/beam/pull/7956
Adds a `withReshuffle` method on JdbcIO classes so reshuffling can be disabled.
This can be useful when an operator immediately after `JdbcIO.Read` reshuffles anyway. In my case I am first reading 20 or so tables and then joining them using a `CoGroupByKey`. Since the CoGroupByKey operation would distribute the data anyway, the work to reshuffle the 20 tables is wasted and results in a much more complex graph than necessary.
There are no tests for this, as reshuffling is not easily testable as it should practically have "no effect". However, there are no tests for the original reparallelization logic either.
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Issue Time Tracking
-------------------
Worklog Id: (was: 205145)
Time Spent: 10m
Remaining Estimate: 0h
> Option to disable reparallelization in JdbcIO.Read
> --------------------------------------------------
>
> Key: BEAM-6670
> URL: https://issues.apache.org/jira/browse/BEAM-6670
> Project: Beam
> Issue Type: Wish
> Components: io-java-jdbc
> Reporter: Mike Pedersen
> Priority: Minor
> Time Spent: 10m
> Remaining Estimate: 0h
>
> I'm doing approx. 20 JDBC queries against a database and then joining them together in a group by. Every single one of these queries does a reshuffle, which is sort of useless due to them being fed to a CoGroupByKey immediately afterwards.
> Reshuffle by default seems sensible by the principle of least surprise, but it would be nice to have a way to disable it when it's not necessary. For example a "withReshuffle(boolean)" method.
> This should be an easy addition and I am willing to add this if it sounds reasonable enough.
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