[ https://issues.apache.org/jira/browse/IMPALA-11323?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Joe McDonnell updated IMPALA-11323: ----------------------------------- Labels: correctness (was: ) > Invalid inferred predicates based on null values being equivalent > ----------------------------------------------------------------- > > Key: IMPALA-11323 > URL: https://issues.apache.org/jira/browse/IMPALA-11323 > Project: IMPALA > Issue Type: Bug > Components: Frontend > Affects Versions: Impala 4.2.0 > Reporter: Joe McDonnell > Priority: Blocker > Labels: correctness > > This query should return two rows, but instead it returns nothing: > {noformat} > [localhost:21050] default> with t as (select 1 a), v as (select distinct a, > cast(null as smallint)b, cast(null as smallint)c from t) select distinct > a,b,c from v union all select distinct a,b,c from v; > Fetched 0 row(s) in 0.14s{noformat} > Without the union all, each side is producing a single row, so it stands to > reason that the union all would produce two rows: > {noformat} > [localhost:21050] default> with t as (select 1 a), v as (select distinct a, > cast(null as smallint)b, cast(null as smallint)c from t) select distinct > a,b,c from v; > +---+------+------+ > | a | b | c | > +---+------+------+ > | 1 | NULL | NULL | > +---+------+------+ > Fetched 1 row(s) in 0.14s > {noformat} > Both b and c are hard coded to null in the definition of v. The plan shows > that it is producing a b = c predicate: > {noformat} > +-------------------------------------------------------------------+ > | Explain String | > +-------------------------------------------------------------------+ > | Max Per-Host Resource Reservation: Memory=7.88MB Threads=1 | > | Per-Host Resource Estimates: Memory=24MB | > | Codegen disabled by planner | > | | > | PLAN-ROOT SINK | > | | | > | 00:UNION | > | | pass-through-operands: all | > | | row-size=5B cardinality=2 | > | | | > | |--08:SELECT | > | | | predicates: b = c | > | | | row-size=5B cardinality=1 | > | | | | > | | 07:AGGREGATE [FINALIZE] | > | | | group by: a, CAST(NULL AS SMALLINT), CAST(NULL AS SMALLINT) | > | | | row-size=5B cardinality=1 | > | | | | > | | 06:AGGREGATE [FINALIZE] | > | | | group by: a, CAST(NULL AS SMALLINT) | > | | | row-size=3B cardinality=1 | > | | | | > | | 05:UNION | > | | constant-operands=1 | > | | row-size=1B cardinality=1 | > | | | > | 04:SELECT | > | | predicates: b = c | > | | row-size=5B cardinality=1 | > | | | > | 03:AGGREGATE [FINALIZE] | > | | group by: a, CAST(NULL AS SMALLINT), CAST(NULL AS SMALLINT) | > | | row-size=5B cardinality=1 | > | | | > | 02:AGGREGATE [FINALIZE] | > | | group by: a, CAST(NULL AS SMALLINT) | > | | row-size=3B cardinality=1 | > | | | > | 01:UNION | > | constant-operands=1 | > | row-size=1B cardinality=1 | > +-------------------------------------------------------------------+ > {noformat} > I added tracing to PlanNode's addConjunctsToNode() and the b=c conjunct is > generated by Analyzer::createEquivConjuncts(). It survives the inferred > identity predicate checks, because it is referring to two different slots. -- This message was sent by Atlassian Jira (v8.20.7#820007) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-all-unsubscr...@impala.apache.org For additional commands, e-mail: issues-all-h...@impala.apache.org