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https://issues.apache.org/jira/browse/IMPALA-11462?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17626391#comment-17626391
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ASF subversion and git services commented on IMPALA-11462:
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Commit b71bdce5ebf8667ae0129ec5fb1d350492d09a46 in impala's branch
refs/heads/dependabot/maven/fe/org.eclipse.jetty-jetty-server-9.4.41.v20210516
from Daniel Becker
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=b71bdce5e ]
IMPALA-11462: Constant folding causes cast on int literals to be lost
The following query returns -128 instead of 128 and the return type is
TINYINT instead of BIGINT:
select shiftleft(cast(1 as bigint), z) c from (select 7 z ) x;
However, if we disable expression rewrites, the result is correct.
The expression rewrite rule 'FoldConstantsRule' folds the the cast to
bigint into the literal during expression rewrite. This modifies the
expression, so re-analysis is needed. Re-analysis resets the literal
expression (a NumericLiteral), which loses its type and becomes TINYINT
again.
'NumericLiteral's have three kinds of type:
- natural type: the smallest type that can hold its value
- explicit type: starts as the natural type and can be widened by
explicit casts
- implicit type: the result of casts the analyzer uses to
adjust input types for functions and arithmetic operations
See NumericLiteral.java for more.
The problem is that when 'FoldConstantsRule' folds the cast into the
literal, it doesn't set its explicit type (only its implicit type
becomes BIGINT). When the expression is reset during re-analysis, the
type is reverted to the incorrect explicit type.
(In the case where expression rewrites are disabled, no re-analysis
takes place so the literal and its type are not reset.)
This patch fixes the error by setting the explicit type of
'NumericLiteral' when folding an explicit cast into it.
Testing:
- Added test
tests/query_test/test_queries.py::TestConstantFoldingNoTypeLoss::test_shiftleft
that tests 'shiftleft' with all integer types.
Change-Id: Ie7f27b204792ef7c59dec5ead363d44ed0c3bc79
Reviewed-on: http://gerrit.cloudera.org:8080/19124
Reviewed-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
> shiftleft problem
> -----------------
>
> Key: IMPALA-11462
> URL: https://issues.apache.org/jira/browse/IMPALA-11462
> Project: IMPALA
> Issue Type: Bug
> Components: Clients
> Affects Versions: Impala 3.4.1
> Reporter: jack sun
> Assignee: Daniel Becker
> Priority: Minor
> Fix For: Impala 4.2.0
>
> Attachments: screenshot-1.png
>
>
> if change the second param of function 'shiftleft' as a dynamic value , it
> will change the first param as tinnyint
> !screenshot-1.png!
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