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https://issues.apache.org/jira/browse/CALCITE-3128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16872709#comment-16872709
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Julian Hyde commented on CALCITE-3128:
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Current behavior is wrong. Cartesian product of one row to one row should
produce one row, regardless of whether columns are null. MySQL and PostgreSQL
are correct.
I think it's very plausible that the problem is in Linq4j. Linq4j tries to be
clever and represents 1-column collections as raw values. Which is fine. But if
"null" also means "was empty" there's a problem. Probably the fix should
include a test for Linq4j hashJoin_ in addition to a SQL-level test.
> Joining two tables producing only NULLs will return 0 rows
> ----------------------------------------------------------
>
> Key: CALCITE-3128
> URL: https://issues.apache.org/jira/browse/CALCITE-3128
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.20.0
> Reporter: Muhammad Gelbana
> Priority: Major
>
> The following queries will return 0 rows while they're expected to ruturn
> rows with NULLs in them.
> {code:sql}
> SELECT *
> FROM (SELECT NULLIF(5, 5)) a, (SELECT NULLIF(5, 5)) b
> {code}
> {code:sql}
> SELECT *
> FROM (VALUES (NULLIF(5, 5)), (NULLIF(5, 5))) a, (VALUES (NULLIF(5, 5)),
> (NULLIF(5, 5))) b
> {code}
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