[GitHub] [hive] vineetgarg02 commented on a change in pull request #860: HIVE-22408 The fix for CALCITE-2991 creates wrong results on edge case

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vineetgarg02 commented on a change in pull request #860: HIVE-22408 The fix for CALCITE-2991 creates wrong results on edge case
URL: https://github.com/apache/hive/pull/860#discussion_r356957099
 
 

 ##########
 File path: ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveSortLimitRemoveRule.java
 ##########
 @@ -41,8 +42,17 @@ public boolean matches(RelOptRuleCall call) {
     final HiveSortLimit sortLimit = call.rel(0);
 
     Double maxRowCount = call.getMetadataQuery().getMaxRowCount(sortLimit.getInput());
-    if (maxRowCount != null &&(maxRowCount <= 1)) {
-      return true;
+    if (maxRowCount != null) {
+      if (sortLimit.getFetchExpr() != null) {
+        // we have LIMIT
+        int limit = RexLiteral.intValue(sortLimit.getFetchExpr());
+        if (maxRowCount <= limit) {
 
 Review comment:
   @kgyrtkirk `MaxRowCount` is guaranteed to return the number of rows which will be >= the actual number of rows, therefore we should never end up removing LIMIT when we shoudn't

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