Gunther Hagleitner created HIVE-4271:
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Summary: Limit precision of decimal type
Key: HIVE-4271
URL: https://issues.apache.org/jira/browse/HIVE-4271
Project: Hive
Issue Type: Bug
Reporter: Gunther Hagleitner
Assignee: Gunther Hagleitner
Attachments: HIVE-4271.1.patch
The current decimal implementation does not limit the precision of the numbers.
This has a number of drawbacks. A maximum precision would allow us to:
- Have SerDes/filformats store decimals more efficiently
- Speed up processing by implementing operations w/o generating java BigDecimals
- Simplify extending the datatype to allow for decimal(p) and decimal(p,s)
- Write a more efficient BinarySortable SerDe for sorting/grouping/joining
Exact numeric datatype are typically used to represent money, so if the limit
is high enough it doesn't really become an issue.
A typical representation would pack 9 decimal digits in 4 bytes. So, with 2
longs we can represent 36 digits - which is what I propose as the limit.
Final thought: It's easier to restrict this now and have the option to do the
things above than to try to do so once people start using the datatype.
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