[HIVE-12063] Pad Decimal numbers with trailing zeros to the scale of the column

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.13.0, 0.14.0, 1.0.0, 1.1.0, 1.2.0
• Fix Version/s: 2.0.0
• Component/s: Types
• Labels: TODOC2.0
• Hadoop Flags: Incompatible change
• Assignee: Xuefu Zhang
• Reporter: Xuefu Zhang
• Created: 07/Oct/15 23:39
• Updated: 24/Nov/20 22:09
• Resolved: 04/Nov/15 03:42

Description

HIVE-7373 was to address the problems of trimming tailing zeros by Hive, which caused many problems including treating 0.0, 0.00 and so on as 0, which has different precision/scale. Please refer to HIVE-7373 description. However, HIVE-7373 was reverted by HIVE-8745 while the underlying problems remained. HIVE-11835 was resolved recently to address one of the problems, where 0.0, 0.00, and so on cannot be read into decimal(1,1).

However, HIVE-11835 didn't address the problem of showing as 0 in query result for any decimal values such as 0.0, 0.00, etc. This causes confusion as 0 and 0.0 have different precision/scale than 0.

The proposal here is to pad zeros for query result to the type's scale. This not only removes the confusion described above, but also aligns with many other DBs. Internal decimal number representation doesn't change, however.

Issue Links

• is related to: HIVE-19523 Decimal truncation for trailing zeros in Hive 1.2.1
• is related to: HIVE-12394 0 is added when you insert decimal value which number of fractional digits is less than defined scale
• relates to: SPARK-28461 Pad Decimal numbers with trailing zeros to the scale of the column
• relates to: HIVE-22139 Will not pad Decimal numbers with trailing zeros if select from value
• relates to: HIVE-24389 Trailing zeros of constant decimal numbers are removed
• relates to: HIVE-7373 Hive should not remove trailing zeros for decimal numbers
• relates to: HIVE-12772 Beeline/JDBC output of decimal values is not 0-padded, does not match with CLI output