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https://issues.apache.org/jira/browse/HIVE-25061?focusedWorklogId=632313&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-632313
 ]

ASF GitHub Bot logged work on HIVE-25061:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 02/Aug/21 12:52
            Start Date: 02/Aug/21 12:52
    Worklog Time Spent: 10m 
      Work Description: abstractdog commented on a change in pull request #2225:
URL: https://github.com/apache/hive/pull/2225#discussion_r680944608



##########
File path: 
ql/src/java/org/apache/hadoop/hive/ql/udf/ptf/ValueBoundaryScanner.java
##########
@@ -664,6 +632,87 @@ public Object computeValue(Object row) throws 
HiveException {
    */
   public abstract boolean isEqual(Object v1, Object v2);
 
+  protected int binarySearchBack(int r, PTFPartition p, Object sortKey, int 
amt,
+      Order order) throws HiveException {
+    boolean isOrderDesc = order.equals(Order.DESC);
+    Object rowVal = sortKey;
+
+    int rMin = -1;  // tracks lowest possible number fulfilling the range 
requirement
+    int rMax = r; // tracks highest possible number fulfilling the range 
requirement
+
+    boolean isDistanceGreater = true;
+    while (true) {
+      if (rMin == rMax) {
+        return rMin;
+      }
+      isDistanceGreater =
+          isDistanceGreater(isOrderDesc ? rowVal : sortKey, isOrderDesc ? 
sortKey : rowVal, amt);
+      if (!isDistanceGreater && r == 0) {
+        return 0;
+      }
+      if (isDistanceGreater) {
+        rMin = r + 1;
+      } else {
+        rMax = r;
+      }
+      r = rMin + (rMax - rMin) / 2;
+      rowVal = computeValueUseCache(r, p);
+    }
+  }
+
+  private int linearSearchBack(int r, PTFPartition p, Object sortKey, int amt,
+      Order order) throws HiveException {
+    boolean isOrderDesc = order.equals(Order.DESC);
+    Object rowVal = sortKey;
+    while (r >= 0 && !isDistanceGreater(isOrderDesc ? rowVal : sortKey,
+        isOrderDesc ? sortKey : rowVal, amt)) {
+      Pair<Integer, Object> stepResult = skipOrStepBack(r, p);
+      r = stepResult.getLeft();
+      rowVal = stepResult.getRight();
+    }
+    return r + 1;
+  }
+
+  protected int binarySearchForward(int r, PTFPartition p, Object sortKey, int 
amt,
+      Order order) throws HiveException {
+    boolean isOrderDesc = order.equals(Order.DESC);
+    Object rowVal = sortKey;
+    int rMin = r;  // tracks lowest possible number fulfilling the range 
requirement
+    int rMax = p.size(); // tracks highest possible number fulfilling the 
range requirement
+
+    boolean isDistanceGreater = true;
+    while (true) {
+      if (rMin == rMax) {
+        return rMin;
+      }
+      isDistanceGreater =
+          isDistanceGreater(isOrderDesc ? sortKey : rowVal, isOrderDesc ? 
rowVal : sortKey, amt);
+      if (!isDistanceGreater && r == p.size() - 1) {

Review comment:
       to stay in line with the current linear implementation, we need to be 
aware that this range end is exclusive
   changing this to p.size()-1 will make TestBoundaryCache fail, showing that 
the binary search led to different results than the linear
   actually it's because p.size() means range will contain every row until 
p.size() exclusive == p.size() - 1 inclusive




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Issue Time Tracking
-------------------

    Worklog Id:     (was: 632313)
    Time Spent: 2h 50m  (was: 2h 40m)

> PTF: Improve ValueBoundaryScanner
> ---------------------------------
>
>                 Key: HIVE-25061
>                 URL: https://issues.apache.org/jira/browse/HIVE-25061
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: László Bodor
>            Assignee: László Bodor
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 4.0.0
>
>         Attachments: Screen Shot 2021-04-27 at 1.02.37 PM.png
>
>          Time Spent: 2h 50m
>  Remaining Estimate: 0h
>
> -First, I need to check whether TreeMap is really needed for our case.-
> It turned out a binary-ish search approach could help in range calculation, 
> as we're searching in an ordered set of values.



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