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Posted to dev@sqoop.apache.org by "Greg Lindholm (JIRA)" <ji...@apache.org> on 2018/02/09 21:27:00 UTC
[jira] [Commented] (SQOOP-3285) Hcatalog import is loosing
precision on DECIMAL fields
[ https://issues.apache.org/jira/browse/SQOOP-3285?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16358981#comment-16358981 ]
Greg Lindholm commented on SQOOP-3285:
--------------------------------------
Patch is attached [^0001-Fix-DECIMAL-percision-loss-with-Hcatalog-imports.patch]
A couple lines added to org.apache.sqoop.mapreduce.hcat.SqoopHCatImportHelper.convertNumberTypes()
The fix is for first check if the value is a BigDecimal or a BigInteger and if so use the value to create the HiveDecimal directly to avoid converting it to a Double.
Here is the logic to new convert a Number into a HiveDecimal.
{code:java}
} else if (hfsType == HCatFieldSchema.Type.DECIMAL) {
if (n instanceof BigDecimal) {
return HiveDecimal.create((BigDecimal)n);
}
if (n instanceof BigInteger) {
return HiveDecimal.create((BigInteger)n);
}
BigDecimal bd = new BigDecimal(n.doubleValue(),
MathContext.DECIMAL128);
return HiveDecimal.create(bd);
}
{code}
> Hcatalog import is loosing precision on DECIMAL fields
> ------------------------------------------------------
>
> Key: SQOOP-3285
> URL: https://issues.apache.org/jira/browse/SQOOP-3285
> Project: Sqoop
> Issue Type: Bug
> Components: hive-integration
> Affects Versions: 1.4.7
> Reporter: Greg Lindholm
> Priority: Major
> Attachments: 0001-Fix-DECIMAL-percision-loss-with-Hcatalog-imports.patch
>
>
> 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:
> {code:java}
> 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'
> {code}
> The result in the hive table does not match the input.
> {noformat}
> Original:
> -123456789012345678901234567890.12345678
> Result:
> -123456789012345677877719597056.00000000{noformat}
> I get the same result with Orc, RCfile, and Avro files.
>
> I believe I found the problem and will provide a patch shortly.
>
>
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