[
https://issues.apache.org/jira/browse/IMPALA-7755?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Paul Rogers reassigned IMPALA-7755:
-----------------------------------
Assignee: (was: Paul Rogers)
Description:
Testing revealed one issue and one limitation of the {{IS [NOT] DISTINCT FROM}}
optimizations in {{SimplifyDistinctFromRule}}.
The rule can simplify {{sum(id) <=> sum(id)}} to {{false}}. But, according to
IMPALA-5125, the rewrite cannot be applied if it would remove the only
aggregate. This is a bug.
A simplification is missing: {{id IS DISTINCT FROM NULL}} → {{id IS NOT
NULL}}.
Here is a specific test case from {{FullRewriteTest}} create as part of
IMPALA-7655:
{code:sql}
@Test
public void TestSimplifyDistinctFromRule() throws ImpalaException {
verifySelectRewrite("if(sum(int_col) <=> sum(int_col), 1, 2)",
"CASE WHEN sum(int_col) IS NOT DISTINCT FROM sum(int_col) THEN 1 ELSE 2
END");
}
{code}
The above fails, the re-writer produces "2" because it ignores the "must
preserve aggregate" rule.
was:
Testing revealed one issue and one limitation of the {{IS [NOT] DISTINCT FROM}}
optimizations in {{SimplifyDistinctFromRule}}.
The rule can simplify {{sum(id) <=> sum(id)}} to {{false}}. But, according to
IMPALA-5125, the rewrite cannot be applied if it would remove the only
aggregate. This is a bug.
A simplification is missing: {{id IS DISTINCT FROM NULL}} → {{id IS NOT
NULL}}.
> IS [NOT] DISTINCT FROM rewrite rules don't handle aggregates
> ------------------------------------------------------------
>
> Key: IMPALA-7755
> URL: https://issues.apache.org/jira/browse/IMPALA-7755
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Affects Versions: Impala 3.0
> Reporter: Paul Rogers
> Priority: Minor
>
> Testing revealed one issue and one limitation of the {{IS [NOT] DISTINCT
> FROM}} optimizations in {{SimplifyDistinctFromRule}}.
> The rule can simplify {{sum(id) <=> sum(id)}} to {{false}}. But, according to
> IMPALA-5125, the rewrite cannot be applied if it would remove the only
> aggregate. This is a bug.
> A simplification is missing: {{id IS DISTINCT FROM NULL}} → {{id IS NOT
> NULL}}.
> Here is a specific test case from {{FullRewriteTest}} create as part of
> IMPALA-7655:
> {code:sql}
> @Test
> public void TestSimplifyDistinctFromRule() throws ImpalaException {
> verifySelectRewrite("if(sum(int_col) <=> sum(int_col), 1, 2)",
> "CASE WHEN sum(int_col) IS NOT DISTINCT FROM sum(int_col) THEN 1 ELSE
> 2 END");
> }
> {code}
> The above fails, the re-writer produces "2" because it ignores the "must
> preserve aggregate" rule.
--
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
