[GitHub] [hive] jcamachor commented on a change in pull request #787: HIVE-22239

[GitBox <gi...@apache.org>]

jcamachor commented on a change in pull request #787: HIVE-22239
URL: https://github.com/apache/hive/pull/787#discussion_r332736102
 
 

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 File path: ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java
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 @@ -935,8 +942,11 @@ else if(colTypeLowerCase.equals(serdeConstants.SMALLINT_TYPE_NAME)){
         cs.setNumTrues(Math.max(1, numRows/2));
         cs.setNumFalses(Math.max(1, numRows/2));
         cs.setAvgColLen(JavaDataModel.get().primitive1());
-    } else if (colTypeLowerCase.equals(serdeConstants.TIMESTAMP_TYPE_NAME) ||
-        colTypeLowerCase.equals(serdeConstants.TIMESTAMPLOCALTZ_TYPE_NAME)) {
+    } else if (colTypeLowerCase.equals(serdeConstants.TIMESTAMP_TYPE_NAME)) {
+      cs.setAvgColLen(JavaDataModel.get().lengthOfTimestamp());
+      // epoch, seconds since epoch
+      cs.setRange(0, 2177452799L);
 
 Review comment:
   I do not think this is critical, but I explored a bit and this seems to be a poor choice for a heuristic, since in most cases it will lead to underestimation of the data size (since most users will not have dates starting from 1970).
   I will take as lower limit `01-01-2015` (epoch for ORC) and as upper limit `12-31-2025`. Let me know if you see any cons with this approach.

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