[CALCITE-7397] Error in simplifying join condition when creating LEFT MARK JOIN

[xiedeyantu]

See CALCITE-7397

Although the issue in Jira has been resolved, this case still generates a nested loop join (mark join), resulting in a new error, albeit a new one, because we haven't yet implemented nested loop join for left_mark join. However, I'll post this issue and its fix here for now, so we can verify it once nested loop join is implemented.

[silundong]

I noticed from the error message that after the subquery was removed the condition of left mark join was FALSE, I think this is the root cause. When the IN subquery is converted to a left mark join, its join condition originally looks like CAST(NULL AS int) = $x. However, inside builder.join the join condition is simplified using an “UNKNOWN AS FALSE” policy. But for a mark join, the marker is a three-valued-logic boolean, so strictly speaking the join condition should be simplified to NULL::BOOLEAN, so maybe we should use “UNKNOWN AS UNKNOWN ” policy for lelf mark join.

[xiedeyantu]

Thank you for pointing out the root cause, which is more correct than my logic for calling convert later. I tried modifying it according to your suggestion, and I'll see if it meets your requirements.

[xiedeyantu]

Quidem cannot be executed at the moment, so I used a different method and added a test in RelOptRulesTest, which also verified the problem.

[silundong]

The code looks great. I have a small suggestion for the title. How about changing it to "Error in simplifying join condition when creating left mark join"? This better reflects the root cause.

[xiedeyantu]

The code looks great. I have a small suggestion for the title. How about changing it to "Error in simplifying join condition when creating left mark join"? This better reflects the root cause.

Done!

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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