Minor Description
When adaptive execution is enabled, an exchange coordinator is used to in the Exchange operators. For Join, the same exchange coordinator is used for its two Exchanges. But the physical plan shows two different coordinator Ids which is confusing.
Here is an example:
== Physical Plan == *Project [key1#3L, value2#12L] +- *SortMergeJoin [key1#3L], [key2#11L], Inner :- *Sort [key1#3L ASC NULLS FIRST], false, 0 : +- Exchange(coordinator id: 1804587700) hashpartitioning(key1#3L, 10), coordinator[target post-shuffle partition size: 67108864] : +- *Project [(id#0L % 500) AS key1#3L] : +- *Filter isnotnull((id#0L % 500)) : +- *Range (0, 1000, step=1, splits=Some(10)) +- *Sort [key2#11L ASC NULLS FIRST], false, 0 +- Exchange(coordinator id: 793927319) hashpartitioning(key2#11L, 10), coordinator[target post-shuffle partition size: 67108864] +- *Project [(id#8L % 500) AS key2#11L, id#8L AS value2#12L] +- *Filter isnotnull((id#8L % 500)) +- *Range (0, 1000, step=1, splits=Some(10))
