[ https://issues.apache.org/jira/browse/IMPALA-7957?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Todd Lipcon reassigned IMPALA-7957: ----------------------------------- Assignee: Quanlong Huang (was: Paul Rogers) > UNION ALL query returns incorrect results > ----------------------------------------- > > Key: IMPALA-7957 > URL: https://issues.apache.org/jira/browse/IMPALA-7957 > Project: IMPALA > Issue Type: Bug > Components: Frontend > Affects Versions: Impala 2.12.0 > Reporter: Luis E Martinez-Poblete > Assignee: Quanlong Huang > Priority: Blocker > Labels: correctness > > Synopsis: > ========= > UNION ALL query returns incorrect results > Problem: > ======== > Customer reported a UNION ALL query returning incorrect results. The UNION > ALL query has 2 legs, but Impala is only returning information from one leg. > Issue can be reproduced in the latest version of Impala. Below is the > reproduction case: > {noformat} > create table mytest_t (c1 timestamp, c2 timestamp, c3 int, c4 int); > insert into mytest_t values (now(), ADDDATE (now(),1), 1,1); > insert into mytest_t values (now(), ADDDATE (now(),1), 2,2); > insert into mytest_t values (now(), ADDDATE (now(),1), 3,3); > SELECT t.c1 > FROM > (SELECT c1, c2 > FROM mytest_t) t > LEFT JOIN > (SELECT c1, c2 > FROM mytest_t > WHERE c2 = c1) t2 ON (t.c2 = t2.c2) > UNION ALL > VALUES (NULL) > {noformat} > The above query produces the following execution plan: > {noformat} > +------------------------------------------------------------------------------------+ > | Explain String > | > +------------------------------------------------------------------------------------+ > | Max Per-Host Resource Reservation: Memory=34.02MB Threads=5 > | > | Per-Host Resource Estimates: Memory=2.06GB > | > | WARNING: The following tables are missing relevant table and/or column > statistics. | > | default.mytest_t > | > | > | > | PLAN-ROOT SINK > | > | | > | > | 06:EXCHANGE [UNPARTITIONED] > | > | | > | > | 00:UNION > | > | | constant-operands=1 > | > | | > | > | 04:SELECT > | > | | predicates: default.mytest_t.c1 = default.mytest_t.c2 > | > | | > | > | 03:HASH JOIN [LEFT OUTER JOIN, BROADCAST] > | > | | hash predicates: c2 = c2 > | > | | > | > | |--05:EXCHANGE [BROADCAST] > | > | | | > | > | | 02:SCAN HDFS [default.mytest_t] > | > | | partitions=1/1 files=3 size=192B > | > | | predicates: c2 = c1 > | > | | > | > | 01:SCAN HDFS [default.mytest_t] > | > | partitions=1/1 files=3 size=192B > | > +------------------------------------------------------------------------------------+ > {noformat} > The issue is in operator 4: > {noformat} > | 04:SELECT | > | | predicates: default.mytest_t.c1 = default.mytest_t.c2 | > {noformat} > It's definitely a bug with predicate placement - that c1 = c2 predicate > shouldn't be evaluated outside the right branch of the LEFT JOIN. > Thanks, > Luis Martinez. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-all-unsubscr...@impala.apache.org For additional commands, e-mail: issues-all-h...@impala.apache.org