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https://issues.apache.org/jira/browse/HIVE-14027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15342133#comment-15342133
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Vaibhav Gumashta commented on HIVE-14027:
-----------------------------------------
Explain output:
{code}
hive> explain select a.n, a.t, isnull(b.n), isnull(b.t) from (select * from
biq998_bigint where n = 1) a left outer join (select * from biq998_bigint
where 1 = 2) b on a.n = b.n;
OK
STAGE DEPENDENCIES:
Stage-4 is a root stage
Stage-3 depends on stages: Stage-4
Stage-0 depends on stages: Stage-3
STAGE PLANS:
Stage: Stage-4
Map Reduce Local Work
Alias -> Map Local Tables:
$hdt$_1:biq998_bigint
Fetch Operator
limit: -1
Alias -> Map Local Operator Tree:
$hdt$_1:biq998_bigint
TableScan
alias: biq998_bigint
Statistics: Num rows: 2 Data size: 10 Basic stats: COMPLETE Column
stats: NONE
Filter Operator
predicate: false (type: boolean)
Statistics: Num rows: 1 Data size: 5 Basic stats: COMPLETE Column
stats: NONE
Select Operator
expressions: n (type: bigint), t (type: string)
outputColumnNames: _col0, _col1
Statistics: Num rows: 1 Data size: 5 Basic stats: COMPLETE
Column stats: NONE
HashTable Sink Operator
keys:
0 1 (type: bigint)
1 _col0 (type: bigint)
Stage: Stage-3
Map Reduce
Map Operator Tree:
TableScan
alias: biq998_bigint
Statistics: Num rows: 2 Data size: 10 Basic stats: COMPLETE Column
stats: NONE
Filter Operator
predicate: (n = 1) (type: boolean)
Statistics: Num rows: 1 Data size: 5 Basic stats: COMPLETE Column
stats: NONE
Select Operator
expressions: t (type: string)
outputColumnNames: _col1
Statistics: Num rows: 1 Data size: 5 Basic stats: COMPLETE
Column stats: NONE
Map Join Operator
condition map:
Left Outer Join0 to 1
keys:
0 1 (type: bigint)
1 _col0 (type: bigint)
outputColumnNames: _col1, _col2, _col3
Statistics: Num rows: 1 Data size: 5 Basic stats: COMPLETE
Column stats: NONE
Select Operator
expressions: 1 (type: bigint), _col1 (type: string), _col2
is null (type: boolean), _col3 is null (type: boolean)
outputColumnNames: _col0, _col1, _col2, _col3
Statistics: Num rows: 1 Data size: 5 Basic stats: COMPLETE
Column stats: NONE
File Output Operator
compressed: false
Statistics: Num rows: 1 Data size: 5 Basic stats:
COMPLETE Column stats: NONE
table:
input format:
org.apache.hadoop.mapred.SequenceFileInputFormat
output format:
org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat
serde:
org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
Local Work:
Map Reduce Local Work
Stage: Stage-0
Fetch Operator
limit: -1
Processor Tree:
ListSink
Time taken: 0.637 seconds, Fetched: 70 row(s)
{code}
Looks like stage-4 after the filter operator should output 0 rows; stats shown
are different.
> NULL values produced by left outer join do not behave as NULL
> -------------------------------------------------------------
>
> Key: HIVE-14027
> URL: https://issues.apache.org/jira/browse/HIVE-14027
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Affects Versions: 1.2.1, 2.0.1
> Reporter: Vaibhav Gumashta
> Assignee: Vaibhav Gumashta
>
> Consider the following setup:
> {code}
> create table tbl (n bigint, t string);
> insert into tbl values (1, 'one');
> insert into tbl values(2, 'two');
> select a.n, a.t, isnull(b.n), isnull(b.t) from (select * from tbl where n =
> 1) a left outer join (select * from tbl where 1 = 2) b on a.n = b.n;
> 1 one false true
> {code}
> The query should return true for isnull(b.n).
> I've tested by inserting a row with null value for the bigint column into
> tbl, and isnull returns true in that case.
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