[GitHub] [druid] techdocsmith commented on a change in pull request #11549: Docs: Clarify segmentMetadata cardinality, minmax, and size behavior.

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techdocsmith commented on a change in pull request #11549:
URL: https://github.com/apache/druid/pull/11549#discussion_r694384889



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File path: docs/querying/segmentmetadataquery.md
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@@ -144,16 +144,27 @@ Types of column analyses are described below:
 
 ### cardinality
 
-* `cardinality` in the result will return the size of the bitmap index or dictionary encoding for string dimensions, or null for other dimension types.
- If `merge` was set, the result will be the max of this value across segments. Only relevant for dimension columns.
+* `cardinality` is the number of unique values present in string columns. It is null for other column types.
+
+This value is computed by examining the size of string column dictionaries. There is one dictionary per column per

Review comment:
       ```suggestion
   Druid examines the size of string column dictionaries to compute the cardinality value. There is one dictionary per column per
   ```




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