Re: [PR] [improvement](statistics)Eliminate null values while sample analyzing ndv. [doris]

["morrySnow (via GitHub)" <gi...@apache.org>]

morrySnow commented on code in PR #50574:
URL: https://github.com/apache/doris/pull/50574#discussion_r2074655187


##########
fe/fe-core/src/main/java/org/apache/doris/statistics/BaseAnalysisTask.java:
##########
@@ -293,16 +293,14 @@ protected String getMinFunction() {
     }
 
     protected String getNdvFunction(String totalRows) {
-        String sampleRows = "SUM(`t1`.`count`)";
-        String onceCount = "SUM(IF(`t1`.`count` = 1, 1, 0))";
-        String countDistinct = "COUNT(1)";
+        String n = "SUM(`t1`.`count`)"; // sample rows
+        String f1 = "SUM(IF(`t1`.`count` = 1 and `t1`.`column_key` is not null, 1, 0))";
+        String d = "SUM(IF(`t1`.`column_key` is not null, 1, 0))"; // sample ndv

Review Comment:
   ```count(`t1`.`column_key`)``` is better?



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