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https://issues.apache.org/jira/browse/BEAM-7194?focusedWorklogId=235941&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-235941
]
ASF GitHub Bot logged work on BEAM-7194:
----------------------------------------
Author: ASF GitHub Bot
Created on: 01/May/19 18:37
Start Date: 01/May/19 18:37
Worklog Time Spent: 10m
Work Description: TheNeuralBit commented on pull request #8447:
[BEAM-7194] EXCEPT DISTINCT behavior when right set contains a value is
incorrect
URL: https://github.com/apache/beam/pull/8447#discussion_r280169297
##########
File path:
sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/transform/BeamSetOperatorsTransforms.java
##########
@@ -97,8 +97,10 @@ public void processElement(ProcessContext ctx) {
}
break;
case MINUS:
- // Say for Row R, there are m instances on left and n instances on
right,
- // EXCEPT ALL outputs MAX(m - n, 0) instances of R.
+ // Say for Row R, there are m instances on left and n instances on
right:
+ // - EXCEPT ALL outputs MAX(m - n, 0) instances of R.
+ // - EXCEPT DISTINCT and EXCEPT output a single instance of R if m >
0 and n == 0, else
Review comment:
Discussed this a bit offline. It looks like the default in Calcite [is in
fact `EXCEPT
DISTINCT`](https://github.com/apache/calcite/blob/master/core/src/main/codegen/templates/Parser.jj#L6011),
and it's actually not mentioned on the calcite reference page. The line we
were both referencing says that `MULTISET EXCEPT` defaults to all. It doesn't
seem to specify `EXCEPT`'s default behavior anywhere.
I'm going to change this comment to `EXCEPT ALL` and `EXCEPT [DISTINCT]` and
resolve this.
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Issue Time Tracking
-------------------
Worklog Id: (was: 235941)
Time Spent: 1h 10m (was: 1h)
> EXCEPT DISTINCT behavior when right set contains a value is incorrect
> ---------------------------------------------------------------------
>
> Key: BEAM-7194
> URL: https://issues.apache.org/jira/browse/BEAM-7194
> Project: Beam
> Issue Type: Bug
> Components: dsl-sql
> Reporter: Brian Hulette
> Assignee: Brian Hulette
> Priority: Major
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> (1, 2, 3, 1) EXCEPT DISTINCT (1) should yield (2, 3), not (1,2,3)
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