[SQOOP-3285] Hcatalog import is loosing precision on DECIMAL fields

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.4.7
• Component/s: hive-integration
• Labels: newbie patch
• Assignee: Unassigned
• Reporter: Greg Lindholm
• Created: 09/Feb/18 19:21
• Updated: 24/Jul/18 14:44

Description

Import with hcatalog for DECIMAL fields is loosing precision.

The bug is in org.apache.sqoop.mapreduce.hcat.SqoopHCatImportHelper.convertNumberTypes()

Internally the BigDecimal value is converted to a Double then back into a BigDecimal.

As a test I imported from a MySQL db a DECIMAL(38,8) field:

create table sampledata1 ( n38 DECIMAL(38,8) );
insert into sampledata1 ( n38 ) values ( -123456789012345678901234567890.12345678 )

sqoop import \
  --connect jdbc:mysql://10.210.144.22:3306/greg --username greg -P \
  -m 1 \
  --table sampledata1 \
  --hcatalog-table sampledata1_orc2 \
  --create-hcatalog-table \
  --hcatalog-storage-stanza 'stored as orc'

The result in the hive table does not match the input.

Original:
-123456789012345678901234567890.12345678
Result:
-123456789012345677877719597056.00000000

I get the same result with Orc, RCfile, and Avro files.

 

I believe I found the problem and will provide a patch shortly.