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From "Hive QA (Jira)" <>
Subject [jira] [Commented] (HIVE-22513) Constant propagation of casted column in filter ops can cause incorrect results
Date Tue, 19 Nov 2019 20:41:00 GMT


Hive QA commented on HIVE-22513:

Here are the results of testing the latest attachment:

{color:red}ERROR:{color} -1 due to no test(s) being added or modified.

{color:red}ERROR:{color} -1 due to 1 failed/errored test(s), 17703 tests executed
*Failed tests:*
TestStatsReplicationScenariosACIDNoAutogather - did not produce a TEST-*.xml file (likely
timed out) (batchId=256)

Test results:
Console output:
Test logs:

Executing org.apache.hive.ptest.execution.TestCheckPhase
Executing org.apache.hive.ptest.execution.PrepPhase
Executing org.apache.hive.ptest.execution.YetusPhase
Executing org.apache.hive.ptest.execution.ExecutionPhase
Executing org.apache.hive.ptest.execution.ReportingPhase
Tests exited with: TestsFailedException: 1 tests failed

This message is automatically generated.

ATTACHMENT ID: 12986234 - PreCommit-HIVE-Build

> Constant propagation of casted column in filter ops can cause incorrect results
> -------------------------------------------------------------------------------
>                 Key: HIVE-22513
>                 URL:
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Ádám Szita
>            Assignee: Ádám Szita
>            Priority: Major
>         Attachments: HIVE-22513.0.patch
> This issue happens if CBO is disabled.
> We should not be propagating constants if the corresponding ExprNodeColumnDesc instance
is wrapped inside a CAST operator as casting might truncate information from the original
> This can happen if we're using CAST in a WHERE clause, which will cause the projected
columns to be replaced in a SELECT operator. Their new value will be the result of casting
which could be a different value compared to that in the original column:
> {code:java}
> set hive.cbo.enable=false;
> set hive.fetch.task.conversion=more; --just for testing convenience
> create table testtb (id string);
> insert into testtb values('2019-11-05 01:01:11');
> select id, CAST(id AS VARCHAR(10)) from testtb where CAST(id AS VARCHAR(9)) = '2019-11-0';
> +------------+------------+
> |     id     |    _c1     |
> +------------+------------+
> | 2019-11-0  | 2019-11-0  |
> +------------+------------+
> 1 row selected (0.168 seconds)
> -- VS expected: 2019-11-05 01:01:11 | 2019-11-05 {code}
> As to what types of casting (from and where types) cause information loss it's hard to
properly keep track of, and I don't think it should be taken into consideration when deciding
whether or not to propagate a constant. Rather than adding a big and potentially convoluted
and fragile check for this, I propose to prevent constant mappings to be spawned out of CASTed

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