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https://issues.apache.org/jira/browse/BEAM-4194?focusedWorklogId=112986&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-112986
]
ASF GitHub Bot logged work on BEAM-4194:
----------------------------------------
Author: ASF GitHub Bot
Created on: 19/Jun/18 03:29
Start Date: 19/Jun/18 03:29
Worklog Time Spent: 10m
Work Description: amaliujia opened a new pull request #5682: [BEAM-4194]
support unbounded limit
URL: https://github.com/apache/beam/pull/5682
##### What?
Support unbounded limit in Beam SQL shell. In the past, due to default
global window and default trigger, queries like "SELECT col_name FROM
unbounded_table LIMIT 1" will not return in SQL Shell.
This PR tries to support unbounded limit by starting a daemon thread to
monitoring return value collection in BeanEnumerableConverter, and stop
pipeline when collected values reach limit count. More detailed description can
be found here:
https://docs.google.com/document/d/13zeTewHH9nfwhSlcE4x77WQwr1U2Z4sTiNRjOXUj2aw/edit?usp=sharing.
##### Testing
- [x] Unit test.
Adding two unit tests to mock bounded and unbounded input tables to test
LIMIT functionality.
- [x] Integration test.
Adding one e2e integration test, which utilizes Google Cloud Pub/Sub to test
the unbounded limit on auto-generated Pub/Sub messages.
- [x] Other test.
Manually tested unbounded limit in Beam SQL shell on a Google Cloud Pub/Sub
table. See the screenshot:
<img width="1041" alt="screen shot 2018-06-18 at 3 48 07 pm"
src="https://user-images.githubusercontent.com/1938382/41574436-106ca752-7336-11e8-91a7-33200513d4b8.png";>
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Issue Time Tracking
-------------------
Worklog Id: (was: 112986)
Time Spent: 10m
Remaining Estimate: 0h
> [SQL] Support LIMIT on Unbounded Data
> -------------------------------------
>
> Key: BEAM-4194
> URL: https://issues.apache.org/jira/browse/BEAM-4194
> Project: Beam
> Issue Type: New Feature
> Components: dsl-sql
> Reporter: Anton Kedin
> Assignee: Rui Wang
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> We need to support queries with "LIMIT xxx".
> Problem is that we don't know when aggregates will trigger, they can
> potentially accumulate values in global window and never trigger.
> If we have some trigger syntax (BEAM-4193), then the use case becomes similar
> to what we have at the moment, where the user defines the trigger upstream
> for all inputs. In this case LIMIT probably can be implemented as
> sample.any(5) with trigger at count.
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