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https://issues.apache.org/jira/browse/HIVE-25582?focusedWorklogId=668121&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-668121
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ASF GitHub Bot logged work on HIVE-25582:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 21/Oct/21 07:14
Start Date: 21/Oct/21 07:14
Worklog Time Spent: 10m
Work Description: dengzhhu653 commented on a change in pull request #2693:
URL: https://github.com/apache/hive/pull/2693#discussion_r733382781
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/exec/LimitOperator.java
##########
@@ -69,8 +69,8 @@ protected void initializeOp(Configuration hconf) throws
HiveException {
this.runtimeCache = ObjectCacheFactory.getCache(getConfiguration(),
queryId, false, true);
// this can happen in HS2 while doing local fetch optimization, where
LimitOperator is used
- if (runtimeCache == null) {
- if (!HiveConf.isLoadHiveServer2Config()) {
+ if (runtimeCache == null || !HiveConf.getVar(hconf,
HiveConf.ConfVars.HIVE_EXECUTION_ENGINE).equals("tez")) {
Review comment:
when the engine is not tez,
[org.apache.hadoop.hive.ql.exec.mr.ObjectCache](https://github.com/apache/hive/blob/1090c93b1a02d480bdee2af2cecf503f8a54efc6/ql/src/java/org/apache/hadoop/hive/ql/exec/ObjectCacheFactory.java#L80-L83)
will be the runtime cache, we do not persist any thing in this cache. so every
time we [fetch the row counter from the
cache](https://github.com/apache/hive/blob/7b3ecf617a6d46f48a3b6f77e0339fd4ad95a420/ql/src/java/org/apache/hadoop/hive/ql/exec/LimitOperator.java#L150-L158),
a newly created AtomicInteger will be returned, the condition `offset <=
currentCountForAllTasksInt`
https://github.com/apache/hive/blob/7b3ecf617a6d46f48a3b6f77e0339fd4ad95a420/ql/src/java/org/apache/hadoop/hive/ql/exec/LimitOperator.java#L98
will be evaluated to false with offset > 0, making the operator unable to
forward any rows to downstream.
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Issue Time Tracking
-------------------
Worklog Id: (was: 668121)
Time Spent: 50m (was: 40m)
> Empty result when using offset limit with MR
> --------------------------------------------
>
> Key: HIVE-25582
> URL: https://issues.apache.org/jira/browse/HIVE-25582
> Project: Hive
> Issue Type: Bug
> Components: Operators
> Affects Versions: 4.0.0
> Reporter: Zhihua Deng
> Assignee: Zhihua Deng
> Priority: Major
> Labels: pull-request-available
> Time Spent: 50m
> Remaining Estimate: 0h
>
> The _mr.ObjectCache_ caches nothing, every time when the limit [retrieving
> global counter from the
> cache|https://github.com/apache/hive/blob/7b3ecf617a6d46f48a3b6f77e0339fd4ad95a420/ql/src/java/org/apache/hadoop/hive/ql/exec/LimitOperator.java#L150-L161],
> a new AtomicInteger will be returned. This make offset _<=
> currentCountForAllTasksInt_ always be evaluated to false, as _offset > 0_,
> the operator will skip all rows.
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