A number of changes have been made to mappings to remove ambiguity and to
ensure that conflicting mappings cannot be created.
One major change is that dynamically added fields must have their mapping
confirmed by the master node before indexing continues. This is to avoid a
problem where different shards in the same index dynamically add different
mappings for the same field. These conflicting mappings can silently return
incorrect results and can lead to index corruption.
This change can make indexing slower when frequently adding many new fields.
We are looking at ways of optimising this process but we chose safety over
performance for this extreme use case.
==== Conflicting field mappings
Fields with the same name, in the same index, in different types, must have
the same mapping, with the exception of the <<copy-to>>, <<dynamic>>,
<<enabled>>, <<ignore-above>>, <<include-in-all>>, and <<properties>>
parameters, which may have different settings per field.
[source,js]
---------------
PUT my_index
{
"mappings": {
"type_one": {
"properties": {
"name": { <1>
"type": "string"
}
}
},
"type_two": {
"properties": {
"name": { <1>
"type": "string",
"analyzer": "english"
}
}
}
}
}
---------------
<1> The two `name` fields have conflicting mappings and will prevent Elasticsearch
from starting.
Elasticsearch will not start in the presence of conflicting field mappings.
These indices must be deleted or reindexed using a new mapping.
The `ignore_conflicts` option of the put mappings API has been removed.
Conflicts can't be ignored anymore.
==== Fields cannot be referenced by short name
A field can no longer be referenced using its short name. Instead, the full
path to the field is required. For instance:
[source,js]
---------------
PUT my_index
{
"mappings": {
"my_type": {
"properties": {
"title": { "type": "string" }, <1>
"name": {
"properties": {
"title": { "type": "string" }, <2>
"first": { "type": "string" },
"last": { "type": "string" }
}
}
}
}
}
}
---------------
<1> This field is referred to as `title`.
<2> This field is referred to as `name.title`.
Previously, the two `title` fields in the example above could have been
confused with each other when using the short name `title`.
==== Type name prefix removed
Previously, two fields with the same name in two different types could
sometimes be disambiguated by prepending the type name. As a side effect, it
would add a filter on the type name to the relevant query. This feature was
ambiguous -- a type name could be confused with a field name -- and didn't
work everywhere e.g. aggregations.
Instead, fields should be specified with the full path, but without a type
name prefix. If you wish to filter by the `_type` field, either specify the
type in the URL or add an explicit filter.
The following example query in 1.x:
[source,js]
----------------------------
GET my_index/_search
{
"query": {
"match": {
"my_type.some_field": "quick brown fox"
}
}
}
----------------------------
would be rewritten in 2.0 as:
[source,js]
----------------------------
GET my_index/my_type/_search <1>
{
"query": {
"match": {
"some_field": "quick brown fox" <2>
}
}
}
----------------------------
<1> The type name can be specified in the URL to act as a filter.
<2> The field name should be specified without the type prefix.
==== Field names may not contain dots
In 1.x, it was possible to create fields with dots in their name, for
instance:
[source,js]
----------------------------
PUT my_index
{
"mappings": {
"my_type": {
"properties": {
"foo.bar": { <1>
"type": "string"
},
"foo": {
"properties": {
"bar": { <1>
"type": "string"
}
}
}
}
}
}
}
----------------------------
<1> These two fields cannot be distinguised as both are referred to as `foo.bar`.
You can no longer create fields with dots in the name.
==== Type names may not start with a dot
In 1.x, Elasticsearch would issue a warning if a type name included a dot,
e.g. `my.type`. Now that type names are no longer used to distinguish between
fields in differnt types, this warning has been relaxed: type names may now
contain dots, but they may not *begin* with a dot. The only exception to this
is the special `.percolator` type.
==== Types may no longer be deleted
In 1.x it was possible to delete a type mapping, along with all of the
documents of that type, using the delete mapping API. This is no longer
supported, because remnants of the fields in the type could remain in the
index, causing corruption later on.
Instead, if you need to delete a type mapping, you should reindex to a new
index which does not contain the mapping. If you just need to delete the
documents that belong to that type, then use the delete-by-query plugin
instead.
[[migration-meta-fields]]
==== Type meta-fields
The <<mapping-fields,meta-fields>> associated with had configuration options
removed, to make them more reliable:
* `_id` configuration can no longer be changed. If you need to sort, use the <<mapping-uid-field,`_uid`>> field instead.
* `_type` configuration can no longer be changed.
* `_index` configuration can no longer be changed.
* `_routing` configuration is limited to marking routing as required.
* `_field_names` configuration is limited to disabling the field.
* `_size` configuration is limited to enabling the field.
* `_timestamp` configuration is limited to enabling the field, setting format and default value.
* `_boost` has been removed.
* `_analyzer` has been removed.
Importantly, *meta-fields can no longer be specified as part of the document
body.* Instead, they must be specified in the query string parameters. For
instance, in 1.x, the `routing` could be specified as follows:
[source,json]
-----------------------------
PUT my_index
{
"mappings": {
"my_type": {
"_routing": {
"path": "group" <1>
},
"properties": {
"group": { <1>
"type": "string"
}
}
}
}
}
PUT my_index/my_type/1 <2>
{
"group": "foo"
}
-----------------------------
<1> This 1.x mapping tells Elasticsearch to extract the `routing` value from the `group` field in the document body.
<2> This indexing request uses a `routing` value of `foo`.
In 2.0, the routing must be specified explicitly:
[source,json]
-----------------------------
PUT my_index
{
"mappings": {
"my_type": {
"_routing": {
"required": true <1>
},
"properties": {
"group": {
"type": "string"
}
}
}
}
}
PUT my_index/my_type/1?routing=bar <2>
{
"group": "foo"
}
-----------------------------
<1> Routing can be marked as required to ensure it is not forgotten during indexing.
<2> This indexing request uses a `routing` value of `bar`.
==== Analyzer mappings
Previously, `index_analyzer` and `search_analyzer` could be set separately,
while the `analyzer` setting would set both. The `index_analyzer` setting has
been removed in favour of just using the `analyzer` setting.
If just the `analyzer` is set, it will be used at index time and at search time. To use a different analyzer at search time, specify both the `analyzer` and a `search_analyzer`.
The `index_analyzer`, `search_analyzer`, and `analyzer` type-level settings
have also been removed, as is is no longer possible to select fields based on
the type name.
The `_analyzer` meta-field, which allowed setting an analyzer per document has
also been removed. It will be ignored on older indices.
==== Date fields and Unix timestamps
Previously, `date` fields would first try to parse values as a Unix timestamp
-- milliseconds-since-the-epoch -- before trying to use their defined date
`format`. This meant that formats like `yyyyMMdd` could never work, as values
would be interpreted as timestamps.
In 2.0, we have added two formats: `epoch_millis` and `epoch_second`. Only
date fields that use these formats will be able to parse timestamps.
These formats cannot be used in dynamic templates, because they are
indistinguishable from long values.
==== Default date format
The default date format has changed from `date_optional_time` to
`strict_date_optional_time`, which expects a 4 digit year, and a 2 digit month
and day, (and optionally, 2 digit hour, minute, and second).
A dynamically added date field, by default, includes the `epoch_millis`
format to support timestamp parsing. For instance:
[source,js]
-------------------------
PUT my_index/my_type/1
{
"date_one": "2015-01-01" <1>
}
-------------------------
<1> Has `format`: `"strict_date_optional_time||epoch_millis"`.
[[migration-bool-fields]]
==== Boolean fields
Boolean fields used to have a string fielddata with `F` meaning `false` and `T`
meaning `true`. They have been refactored to use numeric fielddata, with `0`
for `false` and `1` for `true`. As a consequence, the format of the responses of
the following APIs changed when applied to boolean fields: `0`/`1` is returned
