Github user zuyu commented on a diff in the pull request:
https://github.com/apache/incubator-quickstep/pull/332#discussion_r167114902
--- Diff: query_optimizer/cost_model/StarSchemaSimpleCostModel.cpp ---
@@ -493,7 +493,7 @@ std::size_t
StarSchemaSimpleCostModel::getNumDistinctValues(
return stat.getNumDistinctValues(rel_attr_id);
}
}
- return estimateCardinalityForTableReference(table_reference);
+ return estimateCardinalityForTableReference(table_reference) * 0.1;
--- End diff --
Could you please explain more regarding why `0.1` would be a good guess for
the number of distinct values?
---
