[HIVE-22877] Fix decimal boundary check for casting to Decimal64

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0
• Fix Version/s: 4.0.0-alpha-1
• Component/s: Vectorization
• Labels: pull-request-available
• Assignee: Mustafa İman
• Reporter: Mustafa İman
• Created: 12/Feb/20 00:16
• Updated: 17/Nov/22 08:49
• Resolved: 17/Feb/20 10:16

Description

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. Scale is irrelevant.

Since vectorized generic udf expression takes scale 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:

 

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

 

 

Issue Links

• links to: GitHub Pull Request #905