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https://issues.apache.org/jira/browse/HIVE-25209?focusedWorklogId=619399&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-619399
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ASF GitHub Bot logged work on HIVE-25209:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 06/Jul/21 15:01
Start Date: 06/Jul/21 15:01
Worklog Time Spent: 10m
Work Description: kgyrtkirk commented on a change in pull request #2360:
URL: https://github.com/apache/hive/pull/2360#discussion_r664637117
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/optimizer/StatsOptimizer.java
##########
@@ -397,6 +397,11 @@ else if (getGbyKeyType(cgbyOp) == GbyKeyType.CONSTANT &&
rowCnt == 0) {
if (udaf instanceof GenericUDAFSum) {
// long/double/decimal
ExprNodeDesc desc = aggr.getParameters().get(0);
+ // return null for SUM(1), when the table is empty. Without this,
category = LONG, and the result is 0
+ // instead of NULL.
+ if (desc instanceof ExprNodeConstantDesc && rowCnt == 0) {
+ return oneRow.add(null);
Review comment:
this `return` doesn't look right to me - it may work correctly if you
around only selecting the aggregate - but what happens if you have more?
I believe you should execute `oneRow.add(null)` ; bail out the rest of this
conditional - and let the code continue with the remaining aggregates if there
is any
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Issue Time Tracking
-------------------
Worklog Id: (was: 619399)
Time Spent: 1h 10m (was: 1h)
> SELECT query with SUM function producing unexpected result
> ----------------------------------------------------------
>
> Key: HIVE-25209
> URL: https://issues.apache.org/jira/browse/HIVE-25209
> Project: Hive
> Issue Type: Bug
> Reporter: Soumyakanti Das
> Assignee: Soumyakanti Das
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> Hive: SELECT query with SUM function producing unexpected result
> Problem Statement:
> {noformat}
> SELECT SUM(1) FROM t1;
> ---- result: 0
> SELECT SUM(agg0) FROM (
> SELECT SUM(1) as agg0 FROM t1 WHERE t1.c0 UNION ALL
> SELECT SUM(1) as agg0 FROM t1 WHERE NOT (t1.c0) UNION ALL
> SELECT SUM(1) as agg0 FROM t1 WHERE (t1.c0) IS NULL
> ) as asdf;
> ---- result: null {noformat}
> Steps to reproduce:
> {noformat}
> DROP DATABASE IF EXISTS db5 CASCADE;
> CREATE DATABASE db5;
> use db5;
> CREATE TABLE IF NOT EXISTS t1(c0 boolean, c1 boolean);
> SELECT SUM(1) FROM t1;
> -- result: 0
> SELECT SUM(agg0) FROM (
> SELECT SUM(1) as agg0 FROM t1 WHERE t1.c0 UNION ALL
> SELECT SUM(1) as agg0 FROM t1 WHERE NOT (t1.c0) UNION ALL
> SELECT SUM(1) as agg0 FROM t1 WHERE (t1.c0) IS NULL
> ) as asdf;
> -- result: null {noformat}
> Observations:
> SELECT SUM(1) as agg0 FROM t1 WHERE t1.c0 = t1.c1; – will result in null
> Similarity with postgres,
> both the queries result in null
> Similarity with Impala,
> both the queries result in null
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