427 lines
13 KiB
Plaintext
427 lines
13 KiB
Plaintext
=== Mapping changes
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A number of changes have been made to mappings to remove ambiguity and to
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ensure that conflicting mappings cannot be created.
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One major change is that dynamically added fields must have their mapping
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confirmed by the master node before indexing continues. This is to avoid a
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problem where different shards in the same index dynamically add different
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mappings for the same field. These conflicting mappings can silently return
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incorrect results and can lead to index corruption.
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This change can make indexing slower when frequently adding many new fields.
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We are looking at ways of optimising this process but we chose safety over
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performance for this extreme use case.
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==== Conflicting field mappings
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Fields with the same name, in the same index, in different types, must have
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the same mapping, with the exception of the <<copy-to>>, <<dynamic>>,
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<<enabled>>, <<ignore-above>>, <<include-in-all>>, and <<properties>>
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parameters, which may have different settings per field.
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[source,js]
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---------------
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PUT my_index
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{
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"mappings": {
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"type_one": {
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"properties": {
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"name": { <1>
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"type": "string"
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}
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}
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},
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"type_two": {
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"properties": {
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"name": { <1>
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"type": "string",
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"analyzer": "english"
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}
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}
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}
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}
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}
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---------------
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<1> The two `name` fields have conflicting mappings and will prevent Elasticsearch
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from starting.
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Elasticsearch will not start in the presence of conflicting field mappings.
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These indices must be deleted or reindexed using a new mapping.
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The `ignore_conflicts` option of the put mappings API has been removed.
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Conflicts can't be ignored anymore.
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==== Fields cannot be referenced by short name
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A field can no longer be referenced using its short name. Instead, the full
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path to the field is required. For instance:
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[source,js]
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---------------
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PUT my_index
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{
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"mappings": {
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"my_type": {
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"properties": {
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"title": { "type": "string" }, <1>
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"name": {
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"properties": {
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"title": { "type": "string" }, <2>
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"first": { "type": "string" },
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"last": { "type": "string" }
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}
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}
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}
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}
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}
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}
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---------------
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<1> This field is referred to as `title`.
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<2> This field is referred to as `name.title`.
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Previously, the two `title` fields in the example above could have been
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confused with each other when using the short name `title`.
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==== Type name prefix removed
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Previously, two fields with the same name in two different types could
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sometimes be disambiguated by prepending the type name. As a side effect, it
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would add a filter on the type name to the relevant query. This feature was
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ambiguous -- a type name could be confused with a field name -- and didn't
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work everywhere e.g. aggregations.
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Instead, fields should be specified with the full path, but without a type
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name prefix. If you wish to filter by the `_type` field, either specify the
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type in the URL or add an explicit filter.
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The following example query in 1.x:
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[source,js]
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----------------------------
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GET my_index/_search
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{
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"query": {
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"match": {
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"my_type.some_field": "quick brown fox"
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}
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}
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}
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----------------------------
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would be rewritten in 2.0 as:
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[source,js]
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----------------------------
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GET my_index/my_type/_search <1>
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{
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"query": {
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"match": {
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"some_field": "quick brown fox" <2>
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}
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}
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}
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----------------------------
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<1> The type name can be specified in the URL to act as a filter.
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<2> The field name should be specified without the type prefix.
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==== Field names may not contain dots
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In 1.x, it was possible to create fields with dots in their name, for
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instance:
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[source,js]
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----------------------------
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PUT my_index
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{
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"mappings": {
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"my_type": {
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"properties": {
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"foo.bar": { <1>
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"type": "string"
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},
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"foo": {
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"properties": {
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"bar": { <1>
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"type": "string"
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}
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}
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}
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}
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}
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}
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}
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----------------------------
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<1> These two fields cannot be distinguised as both are referred to as `foo.bar`.
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You can no longer create fields with dots in the name.
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==== Type names may not start with a dot
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In 1.x, Elasticsearch would issue a warning if a type name included a dot,
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e.g. `my.type`. Now that type names are no longer used to distinguish between
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fields in different types, this warning has been relaxed: type names may now
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contain dots, but they may not *begin* with a dot. The only exception to this
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is the special `.percolator` type.
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==== Type names may not be longer than 255 characters
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Mapping type names may not be longer than 255 characters. Long type names
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will continue to function on indices created before upgrade, but it will not
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be possible create types with long names in new indices.
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==== Types may no longer be deleted
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In 1.x it was possible to delete a type mapping, along with all of the
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documents of that type, using the delete mapping API. This is no longer
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supported, because remnants of the fields in the type could remain in the
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index, causing corruption later on.
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Instead, if you need to delete a type mapping, you should reindex to a new
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index which does not contain the mapping. If you just need to delete the
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documents that belong to that type, then use the delete-by-query plugin
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instead.
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[[migration-meta-fields]]
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==== Type meta-fields
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The <<mapping-fields,meta-fields>> associated with had configuration options
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removed, to make them more reliable:
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* `_id` configuration can no longer be changed. If you need to sort, use the <<mapping-uid-field,`_uid`>> field instead.
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* `_type` configuration can no longer be changed.
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* `_index` configuration can no longer be changed.
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* `_routing` configuration is limited to marking routing as required.
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* `_field_names` configuration is limited to disabling the field.
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* `_size` configuration is limited to enabling the field.
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* `_timestamp` configuration is limited to enabling the field, setting format and default value.
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* `_boost` has been removed.
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* `_analyzer` has been removed.
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Importantly, *meta-fields can no longer be specified as part of the document
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body.* Instead, they must be specified in the query string parameters. For
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instance, in 1.x, the `routing` could be specified as follows:
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[source,json]
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-----------------------------
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PUT my_index
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{
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"mappings": {
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"my_type": {
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"_routing": {
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"path": "group" <1>
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},
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"properties": {
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"group": { <1>
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"type": "string"
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}
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}
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}
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}
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}
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PUT my_index/my_type/1 <2>
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{
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"group": "foo"
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}
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-----------------------------
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<1> This 1.x mapping tells Elasticsearch to extract the `routing` value from the `group` field in the document body.
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<2> This indexing request uses a `routing` value of `foo`.
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In 2.0, the routing must be specified explicitly:
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[source,json]
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-----------------------------
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PUT my_index
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{
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"mappings": {
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"my_type": {
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"_routing": {
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"required": true <1>
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},
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"properties": {
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"group": {
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"type": "string"
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}
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}
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}
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}
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}
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PUT my_index/my_type/1?routing=bar <2>
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{
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"group": "foo"
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}
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-----------------------------
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<1> Routing can be marked as required to ensure it is not forgotten during indexing.
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<2> This indexing request uses a `routing` value of `bar`.
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==== `_timestamp` and `_ttl` deprecated
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The `_timestamp` and `_ttl` fields are deprecated, but will remain functional
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for the remainder of the 2.x series.
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Instead of the `_timestamp` field, use a normal <<date,`date`>> field and set
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the value explicitly.
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The current `_ttl` functionality will be replaced in a future version with a
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new implementation of TTL, possibly with different semantics, and will not
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depend on the `_timestamp` field.
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==== Analyzer mappings
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Previously, `index_analyzer` and `search_analyzer` could be set separately,
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while the `analyzer` setting would set both. The `index_analyzer` setting has
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been removed in favour of just using the `analyzer` setting.
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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`.
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The `index_analyzer`, `search_analyzer`, and `analyzer` type-level settings
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have also been removed, as is is no longer possible to select fields based on
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the type name.
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The `_analyzer` meta-field, which allowed setting an analyzer per document has
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also been removed. It will be ignored on older indices.
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==== Date fields and Unix timestamps
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Previously, `date` fields would first try to parse values as a Unix timestamp
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-- milliseconds-since-the-epoch -- before trying to use their defined date
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`format`. This meant that formats like `yyyyMMdd` could never work, as values
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would be interpreted as timestamps.
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In 2.0, we have added two formats: `epoch_millis` and `epoch_second`. Only
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date fields that use these formats will be able to parse timestamps.
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These formats cannot be used in dynamic templates, because they are
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indistinguishable from long values.
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==== Default date format
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The default date format has changed from `date_optional_time` to
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`strict_date_optional_time`, which expects a 4 digit year, and a 2 digit month
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and day, (and optionally, 2 digit hour, minute, and second).
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A dynamically added date field, by default, includes the `epoch_millis`
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format to support timestamp parsing. For instance:
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[source,js]
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-------------------------
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PUT my_index/my_type/1
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{
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"date_one": "2015-01-01" <1>
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}
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-------------------------
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<1> Has `format`: `"strict_date_optional_time||epoch_millis"`.
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[[migration-bool-fields]]
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==== Boolean fields
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Boolean fields used to have a string fielddata with `F` meaning `false` and `T`
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meaning `true`. They have been refactored to use numeric fielddata, with `0`
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for `false` and `1` for `true`. As a consequence, the format of the responses of
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the following APIs changed when applied to boolean fields: `0`/`1` is returned
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instead of `F`/`T`:
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* <<search-request-fielddata-fields,fielddata fields>>
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* <<search-request-sort,sort values>>
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* <<search-aggregations-bucket-terms-aggregation,terms aggregations>>
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In addition, terms aggregations use a custom formatter for boolean (like for
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dates and ip addresses, which are also backed by numbers) in order to return
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the user-friendly representation of boolean fields: `false`/`true`:
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[source,js]
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---------------
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"buckets": [
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{
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"key": 0,
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"key_as_string": "false",
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"doc_count": 42
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},
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{
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"key": 1,
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"key_as_string": "true",
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"doc_count": 12
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}
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]
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---------------
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==== `index_name` and `path` removed
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The `index_name` setting was used to change the name of the Lucene field,
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and the `path` setting was used on `object` fields to determine whether the
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Lucene field should use the full path (including parent object fields), or
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just the final `name`.
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These setting have been removed as their purpose is better served with the
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<<copy-to>> parameter.
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==== Murmur3 Fields
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Fields of type `murmur3` can no longer change `doc_values` or `index` setting.
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They are always mapped as follows:
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[source,js]
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---------------------
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{
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"type": "murmur3",
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"index": "no",
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"doc_values": true
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}
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---------------------
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==== Mappings in config files not supported
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The ability to specify mappings in configuration files has been removed. To
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specify default mappings that apply to multiple indexes, use
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<<indices-templates,index templates>> instead.
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Along with this change, the following settings have been removed:
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* `index.mapper.default_mapping_location`
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* `index.mapper.default_percolator_mapping_location`
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==== Fielddata formats
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Now that doc values are the default for fielddata, specialized in-memory
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formats have become an esoteric option. These fielddata formats have been removed:
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* `fst` on string fields
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* `compressed` on geo points
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The default fielddata format will be used instead.
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==== Posting and doc-values codecs
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It is no longer possible to specify per-field postings and doc values formats
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in the mappings. This setting will be ignored on indices created before 2.0
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and will cause mapping parsing to fail on indices created on or after 2.0. For
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old indices, this means that new segments will be written with the default
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postings and doc values formats of the current codec.
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It is still possible to change the whole codec by using the `index.codec`
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setting. Please however note that using a non-default codec is discouraged as
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it could prevent future versions of Elasticsearch from being able to read the
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index.
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==== Compress and compress threshold
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The `compress` and `compress_threshold` options have been removed from the
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`_source` field and fields of type `binary`. These fields are compressed by
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default. If you would like to increase compression levels, use the new
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<<index-codec,`index.codec: best_compression`>> setting instead.
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==== position_offset_gap
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The `position_offset_gap` option is renamed to 'position_increment_gap'. This was
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done to clear away the confusion. Elasticsearch's 'position_increment_gap' now is
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mapped directly to Lucene's 'position_increment_gap'
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The default `position_increment_gap` is now 100. Indexes created in Elasticsearch
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2.0.0 will default to using 100 and indexes created before that will continue
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to use the old default of 0. This was done to prevent phrase queries from
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matching across different values of the same term unexpectedly. Specifically,
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100 was chosen to cause phrase queries with slops up to 99 to match only within
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a single value of a field.
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