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https://issues.apache.org/jira/browse/HIVE-3976?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13778401#comment-13778401
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Xuefu Zhang commented on HIVE-3976:
-----------------------------------
[~jdere] Thank you very much for your early feedback.
Re: #1. I can see HiveDecimalUtils.java in patch #1.
#2. Thanks for noticing that. I was consolidating this logic but still
forgot this class. It should be synched with other parts of the code.
#3. A type decimal(5,3) signifies that at most two digits are allowed for
integer part because 3 is allocated for decimal part. With this, the biggest
value it can take is 99.999. Thus, a value greater than 99.999 shouldn't be
allowed for this type. Here is what mysql does in default mode:
{code}
mysql> CREATE TABLE t3 (d DECIMAL(5,3));
Query OK, 0 rows affected (0.12 sec)
mysql> insert into t3 values (123.45);
Query OK, 1 row affected, 1 warning (0.04 sec)
mysql> select * from t3;
+--------+
| d |
+--------+
| 99.999 |
+--------+
1 row in set (0.00 sec)
{code}
I believe that under strict mode, the value will be rejected. Since Hive
currently only has a strict mode, we choose null in this case. With other
modes in the future, we may have different behaviour. Regardless, I don't think
decimal(5,3) should hold more than 2 integer digits.
#4. I will check what's the difference between BidDecimal.scale() and
decimal.scale(). In the meantime, could you be specific about what you know of
the difference.
> Support specifying scale and precision with Hive decimal type
> -------------------------------------------------------------
>
> Key: HIVE-3976
> URL: https://issues.apache.org/jira/browse/HIVE-3976
> Project: Hive
> Issue Type: New Feature
> Components: Query Processor, Types
> Reporter: Mark Grover
> Assignee: Xuefu Zhang
> Attachments: HIVE-3976.1.patch, HIVE-3976.patch,
> remove_prec_scale.diff
>
>
> HIVE-2693 introduced support for Decimal datatype in Hive. However, the
> current implementation has unlimited precision and provides no way to specify
> precision and scale when creating the table.
> For example, MySQL allows users to specify scale and precision of the decimal
> datatype when creating the table:
> {code}
> CREATE TABLE numbers (a DECIMAL(20,2));
> {code}
> Hive should support something similar too.
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