[IMPALA-1101] WHERE condition ignored in simple query with RIGHT JOIN

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.0
• Fix Version/s: Impala 2.0
• Labels: correctness
• Assignee: Alexander Behm
• Reporter: casey
• Created: 22/Jul/14 00:11
• Updated: 13/Aug/20 22:13
• Resolved: 08/Aug/14 05:49

Description

This seems to be specific to RIGHT JOIN. If the query is rewritten to use a LEFT JOIN the results are correct.

[localhost:21000] > select 1 FROM alltypes AS t1 RIGHT JOIN alltypestiny AS t2 ON t2.int_col = t1.int_col WHERE false limit 1;
Query: select 1 FROM alltypes AS t1 RIGHT JOIN alltypestiny AS t2 ON t2.int_col = t1.int_col WHERE false limit 1
+---+
| 1 |
+---+
| 1 |
+---+
Returned 1 row(s) in 0.14s


[localhost:21000] > explain select 1 FROM alltypes AS t1 RIGHT JOIN alltypestiny AS t2 ON t2.int_col = t1.int_col WHERE false limit 1;
Query: explain select 1 FROM alltypes AS t1 RIGHT JOIN alltypestiny AS t2 ON t2.int_col = t1.int_col WHERE false limit 1
+----------------------------------------------------------+
| Explain String                                           |
+----------------------------------------------------------+
| Estimated Per-Host Requirements: Memory=32.00MB VCores=2 |
|                                                          |
| 05:EXCHANGE [UNPARTITIONED]                              |
| |  limit: 1                                              |
| |                                                        |
| 02:HASH JOIN [RIGHT OUTER JOIN, PARTITIONED]             |
| |  hash predicates: t1.int_col = t2.int_col              |
| |  limit: 1                                              |
| |                                                        |
| |--04:EXCHANGE [HASH(t2.int_col)]                        |
| |  |                                                     |
| |  01:SCAN HDFS [functional.alltypestiny t2]             |
| |     partitions=4/4 size=460B                           |
| |                                                        |
| 03:EXCHANGE [HASH(t1.int_col)]                           |
| |                                                        |
| 00:SCAN HDFS [functional.alltypes t1]                    |
|    partitions=0/24 size=0B                               |
+----------------------------------------------------------+
Returned 18 row(s) in 0.02s


[localhost:21000] > select 1 FROM alltypestiny AS t1 LEFT JOIN alltypes AS t2 ON t2.int_col = t1.int_col WHERE false limit 1;
Query: select 1 FROM alltypestiny AS t1 LEFT JOIN alltypes AS t2 ON t2.int_col = t1.int_col WHERE false limit 1

Returned 0 row(s) in 0.13s


[localhost:21000] > explain select 1 FROM alltypestiny AS t1 LEFT JOIN alltypes AS t2 ON t2.int_col = t1.int_col WHERE false limit 1;
Query: explain select 1 FROM alltypestiny AS t1 LEFT JOIN alltypes AS t2 ON t2.int_col = t1.int_col WHERE false limit 1
+-----------------------------------------------------------+
| Explain String                                            |
+-----------------------------------------------------------+
| Estimated Per-Host Requirements: Memory=160.03MB VCores=2 |
|                                                           |
| 04:EXCHANGE [UNPARTITIONED]                               |
| |  limit: 1                                               |
| |                                                         |
| 02:HASH JOIN [LEFT OUTER JOIN, BROADCAST]                 |
| |  hash predicates: t1.int_col = t2.int_col               |
| |  limit: 1                                               |
| |                                                         |
| |--03:EXCHANGE [BROADCAST]                                |
| |  |                                                      |
| |  01:SCAN HDFS [functional.alltypes t2]                  |
| |     partitions=24/24 size=478.45KB                      |
| |                                                         |
| 00:SCAN HDFS [functional.alltypestiny t1]                 |
|    partitions=0/4 size=0B                                 |
+-----------------------------------------------------------+
Returned 16 row(s) in 0.01s

Issue Links

• is related to: IMPALA-3094 Incorrect result due to constant evaluation in query with outer join