108 lines
3.1 KiB
Plaintext
108 lines
3.1 KiB
Plaintext
|
[[index-modules-index-sorting]]
|
||
|
|
== Index Sorting
|
||
|
|
|
||
|
|
experimental[]
|
||
|
|
|
||
|
|
When creating a new index in elasticsearch it is possible to configure how the Segments
|
||
|
|
inside each Shard will be sorted. By default Lucene does not apply any sort.
|
||
|
|
The `index.sort.*` settings define which fields should be used to sort the documents inside each Segment.
|
||
|
|
|
||
|
|
[WARNING]
|
||
|
|
nested fields are not compatible with index sorting because they rely on the assumption
|
||
|
|
that nested documents are stored in contiguous doc ids, which can be broken by index sorting.
|
||
|
|
An error will be thrown if index sorting is activated on an index that contains nested fields.
|
||
|
|
|
||
|
|
For instance the following example shows how to define a sort on a single field:
|
||
|
|
|
||
|
|
[source,js]
|
||
|
|
--------------------------------------------------
|
||
|
|
PUT twitter
|
||
|
|
{
|
||
|
|
"settings" : {
|
||
|
|
"index" : {
|
||
|
|
"sort.field" : "date", <1>
|
||
|
|
"sort.order" : "desc" <2>
|
||
|
|
}
|
||
|
|
},
|
||
|
|
"mappings": {
|
||
|
|
"tweet": {
|
||
|
|
"properties": {
|
||
|
|
"date": {
|
||
|
|
"type": "date"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
--------------------------------------------------
|
||
|
|
// CONSOLE
|
||
|
|
|
||
|
|
<1> This index is sorted by the `date` field
|
||
|
|
<2> ... in descending order.
|
||
|
|
|
||
|
|
It is also possible to sort the index by more than one field:
|
||
|
|
|
||
|
|
[source,js]
|
||
|
|
--------------------------------------------------
|
||
|
|
PUT twitter
|
||
|
|
{
|
||
|
|
"settings" : {
|
||
|
|
"index" : {
|
||
|
|
"sort.field" : ["username", "date"], <1>
|
||
|
|
"sort.order" : ["asc", "desc"] <2>
|
||
|
|
}
|
||
|
|
},
|
||
|
|
"mappings": {
|
||
|
|
"tweet": {
|
||
|
|
"properties": {
|
||
|
|
"username": {
|
||
|
|
"type": "keyword",
|
||
|
|
"doc_values": true
|
||
|
|
},
|
||
|
|
"date": {
|
||
|
|
"type": "date"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
--------------------------------------------------
|
||
|
|
// CONSOLE
|
||
|
|
|
||
|
|
<1> This index is sorted by `username` first then by `date`
|
||
|
|
<2> ... in ascending order for the `username` field and in descending order for the `date` field.
|
||
|
|
|
||
|
|
|
||
|
|
Index sorting supports the following settings:
|
||
|
|
|
||
|
|
`index.sort.field`::
|
||
|
|
|
||
|
|
The list of fields used to sort the index.
|
||
|
|
Only `boolean`, `numeric`, `date` and `keyword` fields with `doc_values` are allowed here.
|
||
|
|
|
||
|
|
`index.sort.order`::
|
||
|
|
|
||
|
|
The sort order to use for each field.
|
||
|
|
The order option can have the following values:
|
||
|
|
* `asc`: For ascending order
|
||
|
|
* `desc`: For descending order.
|
||
|
|
|
||
|
|
`index.sort.mode`::
|
||
|
|
|
||
|
|
Elasticsearch supports sorting by multi-valued fields.
|
||
|
|
The mode option controls what value is picked to sort the document.
|
||
|
|
The mode option can have the following values:
|
||
|
|
* `min`: Pick the lowest value.
|
||
|
|
* `max`: Pick the highest value.
|
||
|
|
|
||
|
|
`index.sort.missing`::
|
||
|
|
|
||
|
|
The missing parameter specifies how docs which are missing the field should be treated.
|
||
|
|
The missing value can have the following values:
|
||
|
|
* `_last`: Documents without value for the field are sorted last.
|
||
|
|
* `_first`: Documents without value for the field are sorted first.
|
||
|
|
|
||
|
|
[WARNING]
|
||
|
|
Index sorting can be defined only once at index creation. It is not allowed to add or update
|
||
|
|
a sort on an existing index.
|