big decimal value losed precision

[vpzlin]

Elasticsearch version (bin/elasticsearch --version): 6.4.2 / 6.8.9 / 7.9.0

Plugins installed: [none]

JVM version (java -version): 1.8

OS version (uname -a if on a Unix-like system): CentOS 7.7

Description of the problem including expected versus actual behavior:

Hello, ES team!
There is a precision losing problem when I'm using java client of ElasticSearch.
Will you fix this bug recently? We do need a big decimal in developing financial system.
Thanks very much!

[Development Environment]
JDK: 1.8
ElasticSearch Server Version: 6.4.2 / 6.8.9 / 7.9.0
ElasticSearch Client Version: 6.4.2 / 6.8.9 / 7.9.0

[Mapping]
PUT test_idx/_doc/_mapping
{
"properties": {
"balance":{"type": "double"}
}
}

[Main Codes & Results -- version of java client and ES server: 6.4.2 / 6.8.9]
BigDecimal val = new BigDecimal("12345678901234567890.12345");
JSONObject jsonObject = new JSONObject();
jsonObject.put("balance", val);

/* Single Put */
// The field 'balance' in curl result by shell showed the correct value '12345678901234567890.12345'
client.index(new IndexRequest("test_idx", "_doc", "1").source(jsonObject.toJSONString(), XContentType.JSON)
        ,RequestOptions.DEFAULT);

/* Bulk Load */
// The field 'balance' in curl result by shell showed the precision losing value '1.2345678901234567E19'
BulkRequest bulkRequest = new BulkRequest();
bulkRequest.add(new IndexRequest("test_idx", "_doc", "2").source(jsonObject.toJSONString(), XContentType.JSON));
client.bulk(bulkRequest, RequestOptions.DEFAULT);

[Main Codes & Results -- version of java client and ES server: 7.9.0]
BigDecimal val = new BigDecimal("12345678901234567890.12345");
JSONObject jsonObject = new JSONObject();
jsonObject.put("balance", val);

/* Single Put */
// The field 'balance' in curl result by shell showed the correct value '12345678901234567890.12345'
client.index(new IndexRequest("test_idx").source(jsonObject.toJSONString(), XContentType.JSON)
        ,RequestOptions.DEFAULT);

/* Bulk Load */
// The field 'balance' in curl result by shell showed the precision losing value '1.2345678901234567E19'
BulkRequest bulkRequest = new BulkRequest();
bulkRequest.add(new IndexRequest("test_idx").source(jsonObject.toJSONString(), XContentType.JSON));
client.bulk(bulkRequest, RequestOptions.DEFAULT);

[Debug and Modify code in java client of ES 7.9.0]
From the results above in different version we can see that it'll losing precision when bulk loading data into ES.
So I debugged code, and I found this bug occured in function '_parseSlowFloat(int expType)' of class 'jackon-core-2.10.4.jar/com.fasterxml.jackson.core.base.ParserBase', the value of variable 'expType' is always 0(int value) from begging, it havn't changged, so the non-int numeric value will be regarded as type 'double' always.
And then, I done these:
[1] downloaded the source code 'jackson-core-2.10.4-sources.jar' and decompressed it into my project.
[2] altered code
/********* before /
if (expType == NR_BIGDECIMAL) {
_numberBigDecimal = _textBuffer.contentsAsDecimal();
_numTypesValid = NR_BIGDECIMAL;
} else {
// Otherwise double has to do
_numberDouble = _textBuffer.contentsAsDouble();
_numTypesValid = NR_DOUBLE;
}
/ after *********/
_numberBigDecimal = _textBuffer.contentsAsDecimal();
_numTypesValid = NR_BIGDECIMAL;
[3] rerun bulk load code to ES, field 'balance' in curl result by shell showed the correct value '12345678901234567890.12345'

[jimczi]

Closing in favor of #46934. We don't provide big decimals data type but the feature is discussed in the linked issue.

[vpzlin]

Closing in favor of #46934. We don't provide big decimals data type but the feature is discussed in the linked issue.

Hi, jimczi.
I'm still considering it as a bug. Did you see my description above?
When I downloaded the source code 'jackson-core-2.10.4-sources.jar' and decompressed it into my project, and then altered codes in java class 'ParserBase.java' as below:

/********* codes before *********/
if (expType == NR_BIGDECIMAL) {
_numberBigDecimal = _textBuffer.contentsAsDecimal();
_numTypesValid = NR_BIGDECIMAL;
} else {
// Otherwise double has to do
_numberDouble = _textBuffer.contentsAsDouble();
_numTypesValid = NR_DOUBLE;
}

/********* codes after *********/
_numberBigDecimal = _textBuffer.contentsAsDecimal();
_numTypesValid = NR_BIGDECIMAL;

After finished altering codes, I reran codes of putting single big-decimal record and bulk loaded multi big-decimal records, both of them worked fine, big-decimal value stored correctly into ES(should be queryed by curl shell, not in kibana or web browser).

So, don't you think this is a bug?