Preview transform API
Previews a transform.
Request
POST _transform/_preview
Prerequisites
If the Elasticsearch security features are enabled, you must have the following privileges:
manage_transform
- source index:
read
,view_index_metadata
The built-in transform_admin
role has the manage_transform
privilege.
For more information, see Security privileges and Built-in roles.
Description
This API generates a preview of the results that you will get when you run the create transforms API with the same configuration. It returns a maximum of 100 results. The calculations are based on all the current data in the source index.
It also generates a list of mappings and settings for the destination index. If the destination index does not exist when you start a transform, these are the mappings and settings that are used. These values are determined based on the field types of the source index and the transform aggregations.
There are some limitations that might result in poor mappings. As a work-around, create the destination index or an index template with your preferred mappings before you start the transform.
Request body
description
(Optional, string) Free text description of the transform.
dest
(Optional, object) The destination for the transform.
Properties of dest
index
(Optional, string) The destination index for the transform.
pipeline
(Optional, string) The unique identifier for a pipeline.
frequency
(Optional, time units) The interval between checks for changes in the source indices when the transform is running continuously. Also determines the retry interval in the event of transient failures while the transform is searching or indexing. The minimum value is 1s
and the maximum is 1h
. The default value is 1m
.
pivot
(Required, object) The method for transforming the data. These objects define the pivot function group by
fields and the aggregation to reduce the data.
Properties of pivot
aggregations
oraggs
(Required, object) Defines how to aggregate the grouped data. The following aggregations are supported:
- Average
- Bucket script
- Bucket selector
- Cardinality
- Filter
- Geo bounds
- Geo centroid
- Max
- Min
- Percentiles
- Rare Terms
- Scripted metric
- Sum
- Terms
- Value count
- Weighted average
Transforms support a subset of the functionality in aggregations. See Limitations.
group_by
(Required, object) Defines how to group the data. More than one grouping can be defined per pivot. The following groupings are supported:
source
(Required, object) The source of the data for the transform.
Properties of source
index
(Required, string or array) The source indices for the transform. It can be a single index, an index pattern (for example,
"my-index-*"
), an array of indices (for example,["my-index-000001", "my-index-000002"]
), or an array of index patterns (for example,["my-index-*", "my-other-index-*"]
.query
(Optional, object) A query clause that retrieves a subset of data from the source index. See Query DSL.
sync
(Optional, object) Defines the properties transforms require to run continuously.
Properties of sync
time
(Optional, object) Specifies that the transform uses a time field to synchronize the source and destination indices.
Properties of
analysis_config
delay
(Optional, time units) The time delay between the current time and the latest input data time. The default value is
60s
.field
(Optional, string) The date field that is used to identify new documents in the source.
settings
(Optional, object) Defines optional transform settings.
Properties of settings
docs_per_second
(Optional, float) Specifies a limit on the number of input documents per second. This setting throttles the transform by adding a wait time between search requests. The default value is
null
, which disables throttling.max_page_search_size
(Optional, integer) Defines the initial page size to use for the composite aggregation for each checkpoint. If circuit breaker exceptions occur, the page size is dynamically adjusted to a lower value. The minimum value is
10
and the maximum is10,000
. The default value is500
.
Response body
preview
(array) An array of documents. In particular, they are the JSON representation of the documents that would be created in the destination index by the transform.
generated_dest_index
(object) Contains details about the destination index.
Properties of generated_dest_index
aliases
(object) The aliases for the destination index.
mappings
(object) The mappings for each document in the destination index.
settings
(object) The index settings for the destination index.
Examples
POST _transform/_preview
{
"source": {
"index": "kibana_sample_data_ecommerce"
},
"pivot": {
"group_by": {
"customer_id": {
"terms": {
"field": "customer_id"
}
}
},
"aggregations": {
"max_price": {
"max": {
"field": "taxful_total_price"
}
}
}
}
}
The data that is returned for this example is as follows:
{
"preview" : [
{
"max_price" : 171.0,
"customer_id" : "10"
},
{
"max_price" : 233.0,
"customer_id" : "11"
},
{
"max_price" : 200.0,
"customer_id" : "12"
}
...
],
"generated_dest_index" : {
"mappings" : {
"_meta" : {
"_transform" : {
"transform" : "transform-preview",
"version" : {
"created" : "7.7.0"
},
"creation_date_in_millis" : 1584738236757
},
"created_by" : "transform"
},
"properties" : {
"max_price" : {
"type" : "half_float"
},
"customer_id" : {
"type" : "keyword"
}
}
},
"settings" : {
"index" : {
"number_of_shards" : "1",
"auto_expand_replicas" : "0-1"
}
},
"aliases" : { }
}
}