Github user ravipesala commented on the issue:
https://github.com/apache/carbondata/pull/2665
@xuchuanyin Datamap expression merging is the basic framework feature but
not tested, so we might expect some issues from it as when it was implemented
there were no index datamaps implemented. So we should fix those issues instead
of removing it. It changes the very nature of index datamap itself if you
remove it.
The expected feature should be as follows.
When the user creates index datamap on multiple columns then it should be
treated as a composite index, not an individual index.
The user should create individual datamaps on the columns if he wants an
individual index on the column.
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