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https://issues.apache.org/jira/browse/IMPALA-5821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16657083#comment-16657083
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Andrew Sherman commented on IMPALA-5821:
----------------------------------------
[~grahn] This jira is in code review but I want to check some language with you.
In the extended explain output the newly emitted sql text is prefixed with the
string "Query with implicit casts:"
Does that sound OK?
Example output:
{code:java}
[localhost:21000] default> set explain_level=2;
EXPLAIN_LEVEL set to 2
[localhost:21000] default> explain select * from functional_kudu.alltypestiny
where bigint_col < 1000 / 100;
Query: explain select * from functional_kudu.alltypestiny where bigint_col <
1000 / 100
Query with implicit casts: SELECT * FROM functional_kudu.alltypestiny WHERE
CAST(bigint_col AS DOUBLE) < CAST(10 AS DOUBLE)
Max Per-Host Resource Reservation: Memory=0B Threads=2
Per-Host Resource Estimates: Memory=10MB
Codegen disabled by planner
""
F00:PLAN FRAGMENT [UNPARTITIONED] hosts=1 instances=1
| Per-Host Resources: mem-estimate=4.88MB mem-reservation=0B
thread-reservation=2
PLAN-ROOT SINK
| mem-estimate=0B mem-reservation=0B thread-reservation=0
|
00:SCAN KUDU [functional_kudu.alltypestiny]
predicates: bigint_col < 10
mem-estimate=4.88MB mem-reservation=0B thread-reservation=1
tuple-ids=0 row-size=97B cardinality=1
in pipelines: 00(GETNEXT)
Fetched 15 row(s) in 0.08s
{code}
> Distinguish numeric types and show implicit cast in EXTENDED explain plans
> --------------------------------------------------------------------------
>
> Key: IMPALA-5821
> URL: https://issues.apache.org/jira/browse/IMPALA-5821
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Affects Versions: Impala 2.8.0
> Reporter: Matthew Jacobs
> Assignee: Andrew Sherman
> Priority: Minor
> Labels: supportability, usability
>
> In this plan, it wasn't clear that the constant in the predicate was being
> evaluated to a double. Then the lhs required an implicit cast, and the
> predicate couldn't be pushed to Kudu:
> {code}
> [localhost:21000] > explain select * from functional_kudu.alltypestiny where
> bigint_col < 1000 / 100;
> Query: explain select * from functional_kudu.alltypestiny where bigint_col <
> 1000 / 100
> +---------------------------------------------+
> | Explain String |
> +---------------------------------------------+
> | Per-Host Resource Reservation: Memory=0B |
> | Per-Host Resource Estimates: Memory=10.00MB |
> | Codegen disabled by planner |
> | |
> | PLAN-ROOT SINK |
> | | |
> | 00:SCAN KUDU [functional_kudu.alltypestiny] |
> | predicates: bigint_col < 10 |
> +---------------------------------------------+
> {code}
> We should make it more clear by printing it in a way that makes it clear that
> it's being interpreted as a DOUBLE, e.g. by wrapping in a cast.
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