fix: fall back to Spark for hash join and sort-merge join on non-default collated string keys [Spark 4]#4095
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0lai0 wants to merge 2 commits intoapache:mainfrom
Open
fix: fall back to Spark for hash join and sort-merge join on non-default collated string keys [Spark 4]#40950lai0 wants to merge 2 commits intoapache:mainfrom
0lai0 wants to merge 2 commits intoapache:mainfrom
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coderfender
approved these changes
Apr 26, 2026
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Which issue does this PR close?
Closes #4051
Rationale for this change
Comet hash join and sort-merge join can produce wrong results when join keys use a non-default string collation. This PR makes those joins fall back to Spark instead of executing with byte-level equality.
What changes are included in this PR?
Add collation guards to:
CometHashJoin.doConvertCometSortMergeJoinExec.supportedSortMergeJoinEqualTypeHow are these changes tested?
Added regression tests in
CometCollationSuitefor Broadcast Hash Join, Shuffled Hash Join and Sort-Merge Join collation handling./mvnw -pl spark -Pspark-4.0 -DwildcardSuites=org.apache.spark.sql.CometCollationSuite test./mvnw -pl spark -Pspark-4.0 -DwildcardSuites=org.apache.comet.exec.CometJoinSuite test