# Dynamic mapping stops at a field called "\_id"
**URL:** https://discuss.elastic.co/t/dynamic-mapping-stops-at-a-field-called--id/19589
**Category:** Elasticsearch
**Created:** [September 3, 2014, 10:12am UTC](https://discuss.elastic.co/t/dynamic-mapping-stops-at-a-field-called--id/19589 "2014-09-03T10:12:53Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Andre\_Hansel](https://discuss.elastic.co/u/Andre_Hansel)
#### Post date: [September 3, 2014, 10:12am UTC](https://discuss.elastic.co/t/dynamic-mapping-stops-at-a-field-called--id/19589/1 "2014-09-03T10:12:53Z")
When indexing a document, when there is a field named "\_id" in the source,
the fields that come after this one don't get added to the mapping, even
though they are stored in the \_source:
PUT /megacorp/blah/3
{
"a": "b",
"\_id" : {},
"c": "d"
}
The document got stored:
GET megacorp/blah/\_search
{
"took": 8,
"timed\_out": false,
"\_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max\_score": 1,
"hits": [
{
"\_index": "megacorp",
"\_type": "blah",
"\_id": "3",
"\_score": 1,
"\_source": {
"a": "b",
"\_id": {},
"c": "d"
}
}
]
}
}
But no mapping was added for "c":
GET /megacorp/\_mapping/blah
{
"megacorp": {
"mappings": {
"blah": {
"properties": {
"a": {
"type": "string"
}
}
}
}
}
}
Is this expected behavior?
Regards,
André
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### Author:  [@Ivan](https://discuss.elastic.co/u/Ivan)
#### Post date: [September 3, 2014, 11:59pm UTC](https://discuss.elastic.co/t/dynamic-mapping-stops-at-a-field-called--id/19589/2 "2014-09-03T23:59:00Z")
The \_id field is one of the few reserved field names in Elasticsearch:
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You can set it to whatever you want, as long as it is not an object or
(empty) array, as in your case. I have no idea what the proper behavior
should be when you try to index bad data to this field, but I am not
surprised that there are issues.
--
Ivan
On Wed, Sep 3, 2014 at 3:12 AM, André Hänsel [andre@webkr.de](mailto:andre@webkr.de) wrote:
> When indexing a document, when there is a field named "\_id" in the source,
> the fields that come after this one don't get added to the mapping, even
> though they are stored in the \_source:
>
> PUT /megacorp/blah/3
> {
> "a": "b",
> "\_id" : {},
> "c": "d"
> }
>
> The document got stored:
>
> GET megacorp/blah/\_search
> {
> "took": 8,
> "timed\_out": false,
> "\_shards": {
> "total": 5,
> "successful": 5,
> "failed": 0
> },
> "hits": {
> "total": 1,
> "max\_score": 1,
> "hits": [
> {
> "\_index": "megacorp",
> "\_type": "blah",
> "\_id": "3",
> "\_score": 1,
> "\_source": {
> "a": "b",
> "\_id": {},
> "c": "d"
> }
> }
> ]
> }
> }
>
> But no mapping was added for "c":
>
> GET /megacorp/\_mapping/blah
> {
> "megacorp": {
> "mappings": {
> "blah": {
> "properties": {
> "a": {
> "type": "string"
> }
> }
> }
> }
> }
> }
>
> Is this expected behavior?
>
> Regards,
> André
>
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---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 1:04am UTC](https://discuss.elastic.co/t/dynamic-mapping-stops-at-a-field-called--id/19589/3 "2017-07-06T01:04:29Z")