[jira] [Commented] (CALCITE-2620) Simplify "coalesce(null,x)" to "x"
[ https://issues.apache.org/jira/browse/CALCITE-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16649790#comment-16649790 ] Julian Hyde commented on CALCITE-2620: -- You’d be surprised how often “no brainer” optimizations come up in generated code, or following view expansions. But there’s a great example of COALESCE within Calcite itself. If you write “select * from emp full join dept using (deptno)” then there will be only one “deptno” column in the output. Calcite will populate it using “coalesce(emp.deptno, dept.deptno)”. If “emp” is a view and its “deptno” column is defined to be “null” then we will end up with “coalesce(null, dept.deptno)”. > Simplify "coalesce(null,x)" to "x" > -- > > Key: CALCITE-2620 > URL: https://issues.apache.org/jira/browse/CALCITE-2620 > Project: Calcite > Issue Type: Improvement > Components: core >Affects Versions: 1.18.0 >Reporter: pengzhiwei >Assignee: Julian Hyde >Priority: Major > > "coalesce(x0,x1,.)" can be simplified if any of "xi" is null literal. > e.g. "coalesce(null,x)" can simplify to "x", "coalesce(x,null,y)" can > simplify to "coalesce(x,y)" -- This message was sent by Atlassian JIRA (v7.6.3#76005)
[jira] [Commented] (CALCITE-2620) Simplify "coalesce(null,x)" to "x"
[ https://issues.apache.org/jira/browse/CALCITE-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16649717#comment-16649717 ] zhen wang commented on CALCITE-2620: [~pzw2018] while this optimization surely looks reasonable, can I ask under what circumstances would people/software write such an expression ? > Simplify "coalesce(null,x)" to "x" > -- > > Key: CALCITE-2620 > URL: https://issues.apache.org/jira/browse/CALCITE-2620 > Project: Calcite > Issue Type: Improvement > Components: core >Affects Versions: 1.18.0 >Reporter: pengzhiwei >Assignee: Julian Hyde >Priority: Major > > "coalesce(x0,x1,.)" can be simplified if any of "xi" is null literal. > e.g. "coalesce(null,x)" can simplify to "x", "coalesce(x,null,y)" can > simplify to "coalesce(x,y)" -- This message was sent by Atlassian JIRA (v7.6.3#76005)
[jira] [Commented] (CALCITE-2620) Simplify "coalesce(null,x)" to "x"
[ https://issues.apache.org/jira/browse/CALCITE-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16648733#comment-16648733 ] pengzhiwei commented on CALCITE-2620: - [~julianhyde],In -CALCITE-2506- this issue has not fixed. I fix it in the [PR882|[http://example.com|https://github.com/apache/calcite/pull/882]] > Simplify "coalesce(null,x)" to "x" > -- > > Key: CALCITE-2620 > URL: https://issues.apache.org/jira/browse/CALCITE-2620 > Project: Calcite > Issue Type: Improvement > Components: core >Affects Versions: 1.18.0 >Reporter: pengzhiwei >Assignee: Julian Hyde >Priority: Major > > "coalesce(x0,x1,.)" can be simplified if any of "xi" is null literal. > e.g. "coalesce(null,x)" can simplify to "x", "coalesce(x,null,y)" can > simplify to "coalesce(x,y)" -- This message was sent by Atlassian JIRA (v7.6.3#76005)
[jira] [Commented] (CALCITE-2620) Simplify "coalesce(null,x)" to "x"
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https://issues.apache.org/jira/browse/CALCITE-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16648648#comment-16648648
]
Julian Hyde commented on CALCITE-2620:
--
In the fix to CALCITE-2506 I see {code}checkSimplify2(coalesce(gt(nullInt,
nullInt), trueLiteral),
"COALESCE(null, true)", "COALESCE(null, true)");{code}
The fact that "COALESCE(null, true)" remains in the simplified result, rather
than having been further simplified to "true", implies that this bug is not
fixed.
> Simplify "coalesce(null,x)" to "x"
> --
>
> Key: CALCITE-2620
> URL: https://issues.apache.org/jira/browse/CALCITE-2620
> Project: Calcite
> Issue Type: Improvement
> Components: core
>Affects Versions: 1.18.0
>Reporter: pengzhiwei
>Assignee: Julian Hyde
>Priority: Major
>
> "coalesce(x0,x1,.)" can be simplified if any of "xi" is null literal.
> e.g. "coalesce(null,x)" can simplify to "x", "coalesce(x,null,y)" can
> simplify to "coalesce(x,y)"
--
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[jira] [Commented] (CALCITE-2620) Simplify "coalesce(null,x)" to "x"
[ https://issues.apache.org/jira/browse/CALCITE-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16646120#comment-16646120 ] Haisheng Yuan commented on CALCITE-2620: This can be fixed using patch in https://github.com/apache/calcite/pull/836/files, which I closed. > Simplify "coalesce(null,x)" to "x" > -- > > Key: CALCITE-2620 > URL: https://issues.apache.org/jira/browse/CALCITE-2620 > Project: Calcite > Issue Type: Improvement > Components: core >Affects Versions: 1.18.0 >Reporter: pengzhiwei >Assignee: Julian Hyde >Priority: Major > > "coalesce(x0,x1,.)" can be simplified if any of "xi" is null literal. > e.g. "coalesce(null,x)" can simplify to "x", "coalesce(x,null,y)" can > simplify to "coalesce(x,y)" -- This message was sent by Atlassian JIRA (v7.6.3#76005)
