[jira] [Commented] (IMPALA-6340) There is no error when inserting an invalid value into a decimal column under decimal_v2

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    [ https://issues.apache.org/jira/browse/IMPALA-6340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16457366#comment-16457366 ] 

ASF subversion and git services commented on IMPALA-6340:
---------------------------------------------------------

Commit d0f838b66a935310de9aeae7b9ba6513a5197ba9 in impala's branch refs/heads/master from [~tarasbob]
[ https://git-wip-us.apache.org/repos/asf?p=impala.git;h=d0f838b ]

IMPALA-6340,IMPALA-6518: Check that decimal types are compatible in FE

In this patch we implement strict decimal type checking in the FE in
various situations when DECIMAL_V2 is enabled. What is affected:
- Union. If we union two decimals and it is not possible to come up
  with a decimal that will be able to contain all the digits, an error
  is thrown. For example, the union(decimal(20, 10), decimal(20, 20))
  returns decimal(30, 20). However, for union(decimal(38, 0),
  decimal(38, 38)) the ideal return type would be decimal(76,38), but
  this is too large, so an error is thrown.
- Insert. If we are inserting a decimal value into a column where we are
  not guaranteed that all digits will fit, an error is thrown. For
  example, inserting a decimal(38,0) value into a decimal(38,38) column.
- Functions such as coalesce(). If we are unable to determine the output
  type that guarantees that all digits will fit from all the arguments,
  an error is thrown. For example,
  coalesce(decimal(38,38), decimal(38,0)) will throw an error.
- Hash Join. When joining on two decimals, if a type cannot be
  determined that both columns can be cast to, we throw an error.
  For example, join on decimal(38,0) and decimal(38,38) will result
  in an error.

To avoid these errors, you need to use CAST() on some of the decimals.

In this patch we also change the output decimal calculation of decimal
round, truncate and related functions. If these functions are a no-op,
the resulting decimal type is the same as the input type.

Testing:
- Ran a core build which passed.

Change-Id: Id406f4189e01a909152985fabd5cca7a1527a568
Reviewed-on: http://gerrit.cloudera.org:8080/9930
Reviewed-by: Alex Behm <al...@cloudera.com>
Tested-by: Impala Public Jenkins <im...@cloudera.com>


> There is no error when inserting an invalid value into a decimal column under decimal_v2
> ----------------------------------------------------------------------------------------
>
>                 Key: IMPALA-6340
>                 URL: https://issues.apache.org/jira/browse/IMPALA-6340
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Backend
>    Affects Versions: Impala 2.11.0
>            Reporter: Taras Bobrovytsky
>            Assignee: Taras Bobrovytsky
>            Priority: Blocker
>              Labels: correctness
>
> The following series of commands does not result in an error or a warning when decimal_v2 is enabled.
> {code}
> set decimal_v2=1;
> create table t1 (c1 decimal(38,37));
> insert into t1 select 11.11;
> {code}
> We end up inserting a NULL into the column without any warnings.
> If these commands are executed with decimal_v2 disabled, we get the following warning:
> {code}
> WARNINGS: UDF WARNING: Decimal expression overflowed, returning NULL
> {code}



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