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https://issues.apache.org/jira/browse/NIFI-7159?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17041000#comment-17041000
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Mike Thomsen commented on NIFI-7159:
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[~Xeinn] I'll work the patch. Don't worry about it.
> Mongo processors appear to not support Decimal 128 data types
> -------------------------------------------------------------
>
> Key: NIFI-7159
> URL: https://issues.apache.org/jira/browse/NIFI-7159
> Project: Apache NiFi
> Issue Type: Bug
> Reporter: Mike Thomsen
> Assignee: Mike Thomsen
> Priority: Major
>
> This is the verbatim response from the user posting on nifi-dev:
>
> *_Here’s a really stripped back example._*
>
> *_I have an input as below_*
>
> *_{_*
> *_"value": "123456.00"_*
> *_}_*
>
> *_And I want to write the value into MongoDB as a numeric value, but
> critically not as a double (these will be currency values)_*
>
> *_In order to try to enforce the type used to write to Mongo we created a
> simple Avro schema, for the example above this would be as follows;_*
>
> *_{_*
> *_"type": "record",_*
> *_"name": "TransactionEvent",_*
> *_"namespace": "com.example.demo",_*
> *_"fields": [_*
> *_{_*
> *_"name": "value",_*
> *_"type": [_*
> *_"null",_*
> *_{_*
> *_"type": "bytes",_*
> *_"logicalType": "decimal",_*
> *_"precision": 10,_*
> *_"scale": 2_*
> *_}_*
> *_]_*
> *_}_*
> *_]_*
> *_}_*
>
> *_Hoping that this would map to a Decimal128 in Mongo, however we
> consistently see double as the type in Mongo regardless of any variations of
> Avro schema we have tried._*
>
> *_On having a quick look into the code I’ve identified 2 possible problem
> areas._*
>
>
> *_1. The conversion of the Avro schema into the internal representation
> which seems to treat Avro logical decimal types as double (ref
> org.apache.nifi.avro.AvroTypeUtil – line 343)_*
> *_2. The Mongo processor which uses this type information to decide what
> Mongo types to persist data as._*
>
> *_For a quick win, which would hopefully have a smaller impact, I was hoping
> that I could fork the Mongo processor and keep the changes local to that but
> since the information about the Avro logical type is lost before the schema
> information gets to MongoDB i’m not sure that will be possible now._*
>
> *_When we reached this point and the changes we were looking at seemed like
> they could be a little more complex than hoped we wanted to reach out to see
> if_*
>
>
> *_1. We’re doing something wrong_*
> *_2. Anybody else had encountered a similar situation_*
> *_3. If we did look to introduce changes either to the Mongo processor or
> more widely for support of BigDecimal would this be of wider use?_*
>
> It would appear to be a distinctly different type than Double:
>
> https://mongodb.github.io/mongo-java-driver/3.5/javadoc/?org/bson/types/Decimal128.html
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