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https://issues.apache.org/jira/browse/HIVE-21217?focusedWorklogId=199293&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-199293
]
ASF GitHub Bot logged work on HIVE-21217:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 15/Feb/19 15:39
Start Date: 15/Feb/19 15:39
Worklog Time Spent: 10m
Work Description: pvary commented on pull request #538: HIVE-21217:
Optimize range calculation for PTF
URL: https://github.com/apache/hive/pull/538#discussion_r257278647
##########
File path:
ql/src/java/org/apache/hadoop/hive/ql/udf/ptf/ValueBoundaryScanner.java
##########
@@ -44,10 +49,207 @@ public ValueBoundaryScanner(BoundaryDef start,
BoundaryDef end, boolean nullsLas
this.nullsLast = nullsLast;
}
+ public abstract Object computeValue(Object row) throws HiveException;
+
+ /**
+ * Checks if the distance of v2 to v1 is greater than the given amt.
+ * @return True if the value of v1 - v2 is greater than amt or either value
is null.
+ */
+ public abstract boolean isDistanceGreater(Object v1, Object v2, int amt);
+
+ /**
+ * Checks if the values of v1 or v2 are the same.
+ * @return True if both values are the same or both are nulls.
+ */
+ public abstract boolean isEqual(Object v1, Object v2);
+
public abstract int computeStart(int rowIdx, PTFPartition p) throws
HiveException;
public abstract int computeEnd(int rowIdx, PTFPartition p) throws
HiveException;
+ /**
+ * Checks and maintains cache content - optimizes cache window to always be
around current row
+ * thereby makes it follow the current progress.
+ * @param rowIdx current row
+ * @param p current partition for the PTF operator
+ * @throws HiveException
+ */
+ public void handleCache(int rowIdx, PTFPartition p) throws HiveException {
+ BoundaryCache cache = p.getBoundaryCache();
+ if (cache == null) {
+ return;
+ }
+
+ //Start of partition
+ if (rowIdx == 0) {
+ cache.clear();
+ }
+ if (cache.isComplete()) {
+ return;
+ }
+
+ int cachePos = cache.approxCachePositionOf(rowIdx);
+
+ if (cache.isEmpty()) {
+ fillCacheUntilEndOrFull(rowIdx, p);
+ } else if (cachePos > 50 && cachePos <= 75) {
Review comment:
This is strange to me. Do we know the size of the window in advance? Shall
we not use our cache accordingly? If the window size is 5 then we should cache
the 7 values (1 before, 1 after, and the 5 values)?
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Issue Time Tracking
-------------------
Worklog Id: (was: 199293)
Time Spent: 20m (was: 10m)
> Optimize range calculation for PTF
> ----------------------------------
>
> Key: HIVE-21217
> URL: https://issues.apache.org/jira/browse/HIVE-21217
> Project: Hive
> Issue Type: Improvement
> Reporter: Adam Szita
> Assignee: Adam Szita
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-21217.0.patch, HIVE-21217.1.patch,
> HIVE-21217.2.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> During window function execution Hive has to iterate on neighbouring rows of
> the current row to find the beginning and end of the proper range (on which
> the aggregation will be executed).
> When we're using range based windows and have many rows with a certain key
> value this can take a lot of time. (e.g. partition size of 80M, in which we
> have 2 ranges of 40M rows according to the orderby column: within these 40M
> rowsets we're doing 40M x 40M/2 steps.. which is of n^2 time complexity)
> I propose to introduce a cache that keeps track of already calculated range
> ends so it can be reused in future scans.
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