[jira] [Commented] (HIVE-22877) Fix decimal boundary check for casting to Decimal64

["Gopal Vijayaraghavan (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-22877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17035080#comment-17035080 ] 

Gopal Vijayaraghavan commented on HIVE-22877:
---------------------------------------------

+1 tests pending.

> Fix decimal boundary check for casting to Decimal64
> ---------------------------------------------------
>
>                 Key: HIVE-22877
>                 URL: https://issues.apache.org/jira/browse/HIVE-22877
>             Project: Hive
>          Issue Type: Bug
>          Components: Vectorization
>    Affects Versions: 4.0.0
>            Reporter: Mustafa Iman
>            Assignee: Mustafa Iman
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: HIVE-22877.patch
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> During vectorization, decimal fields that are obtained via generic udfs are cast to Decimal64 in some circumstances. For decimal to decimal64 cast, hive compares the source column's `scale + precision` to 18(maximum number of digits that can be represented by a long). A decimal can fit in a long as long as its `precision` is smaller than or equal to 18. Precision is irrelevant.
> Since vectorized generic udf expression takes precision into account, it computes wrong output column vector: Decimal instead of Decimal64. This in turn causes ClassCastException down the operator chain.
> Below query fails with class cast exception:
>  
> {code:java}
> create table mini_store
> (
>  s_store_sk int,
>  s_store_id string
> )
> row format delimited fields terminated by '\t'
> STORED AS ORC;
> create table mini_sales
> (
>  ss_store_sk int,
>  ss_quantity int,
>  ss_sales_price decimal(7,2)
> )
> row format delimited fields terminated by '\t'
> STORED AS ORC;
> insert into mini_store values (1, 'store');
> insert into mini_sales values (1, 2, 1.2);
> select s_store_id, coalesce(ss_sales_price*ss_quantity,0) sumsales
> from mini_sales, mini_store where ss_store_sk = s_store_sk
> {code}
>  
>  



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