The crash happens when none of the if-else branch of handle_missing_partition()
evaluates and returns merged_index unassigned.
Let me explain, in Rajkumar 's test case, the join type is JOIN_INNER. When
only outer rel has null partition, merge_null_partitions() function calls
handle_missing_partition() with missing_side_inner = false and
missing_side_outer = false
Both missing_side_ variables being false when the NULL partition is missing on the inner side looks suspicious. I guess from the variable names that the missing_side_inner should be true in this case.
argument value which fails to set merged_index.
In the attached patch, I tried to fix this case by setting merged_index
explicitly which fixes the reported crash.
I expect handle_missing_partition() to set the merged_index always. In your patches, I don't see that function in your patches is setting it explicitly. If we are setting merged_index explicitly somewhere else, other places may miss that explicit assignment. So it's better to move it inside this function.
