Github user qiuchenjian commented on the issue:
https://github.com/apache/carbondata/pull/3025
> @qiuchenjian currently pre-aggregate datamap is not following the datamap
interfaces as it was implemented before datamap framework. That is why not all
datamap DDL works with pre-aggregate. It is better to keep the pre-aggregate
datamap untouched in this area until we decide whether to take MV datamap or
pre-aggregate datamap.
@ravipesala OK, I will close this PR. But "show datamap" can't return
preaggregate ,but it's still called datamap, which is strange.
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