Preview a transform
- POST also GET /_transform/{transform_id}/_preview
- POST also GET /_transform/_preview
Generates a preview of the results that you will get when you create a transform 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. These values are determined based on the field types of the source index and the transform aggregations.
Required authorization
- Index privileges read view_index_metadata
- Cluster privileges manage_transform
Request body
-
destobject -
The destination for the transform.
-
indexstring -
The destination index for the transform. The mappings of the destination index are deduced based on the source fields when possible. If alternate mappings are required, use the create index API prior to starting the transform.
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aliasesobject -
The aliases that the destination index for the transform should have. Aliases are manipulated using the stored credentials of the transform, which means the secondary credentials supplied at creation time (if both primary and secondary credentials are specified).
The destination index is added to the aliases regardless of whether the destination index was created by the transform or pre-created by the user.
-
move_on_creationboolean · default: false -
Whether the destination index should be the only index in this alias. If
true, all the other indices will be removed from this alias before adding the destination index to this alias. This does not delete the removed indices; it only removes them from the alias. -
frequencystring · default: 1m -
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.
-
pivotobject -
The pivot method transforms the data by aggregating and grouping it. These objects define the group by fields and the aggregation to reduce the data.
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aggregationsmap string to Aggregation -
Defines how to aggregate the grouped data. The following aggregations are currently supported: average, bucket script, bucket selector, cardinality, filter, geo bounds, geo centroid, geo line, max, median absolute deviation, min, missing, percentiles, rare terms, scripted metric, stats, sum, terms, top metrics, value count, weighted average.
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group_bymap string to object -
Defines how to group the data. More than one grouping can be defined per pivot. The following groupings are currently supported: date histogram, geotile grid, histogram, terms.
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<string>object · min properties: 1 · max properties: 1 -
date_histogramobject -
calendar_interval -
Calendar-aware interval. Can be specified using the unit name, such as
month, or as a single unit quantity, such as1M. -
Values:
second1sminute1mhour1hday1dweek1wmonth1Mquarter1qyear1y -
fixed_intervalstring -
Fixed intervals: a fixed number of SI units and never deviate, regardless of where they fall on the calendar.
-
formatstring -
The date format used to format
key_as_stringin the response. If noformatis specified, the first date format specified in the field mapping is used. -
min_doc_countnumber -
Only returns buckets that have
min_doc_countnumber of documents. By default, all buckets between the first bucket that matches documents and the last one are returned. -
missingunion -
The value to apply to documents that do not have a value. By default, documents without a value are ignored.
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offsetstring -
Changes the start value of each bucket by the specified positive (
+) or negative offset (-) duration. -
geotile_gridobject -
histogramobject -
hard_boundsobject -
Limits the range of buckets in the histogram. It is particularly useful in the case of open data ranges that can result in a very large number of buckets.
-
min_doc_countnumber -
Only returns buckets that have
min_doc_countnumber of documents. By default, the response will fill gaps in the histogram with empty buckets. -
missingnumber -
The value to apply to documents that do not have a value. By default, documents without a value are ignored.
-
offsetnumber -
By default, the bucket keys start with 0 and then continue in even spaced steps of
interval. The bucket boundaries can be shifted by using theoffsetoption. -
termsobject -
collect_mode -
Determines how child aggregations should be calculated: breadth-first or depth-first.
Supported values include:
depth_first: Expands all branches of the aggregation tree in one depth-first pass, before any pruning occurs.breadth_first: Caches the set of documents that fall into the uppermost buckets for subsequent replay.
-
Values:
depth_firstbreadth_first -
execution_hint -
Determines whether the aggregation will use field values directly or global ordinals.
-
Values:
mapglobal_ordinalsglobal_ordinals_hashglobal_ordinals_low_cardinality -
min_doc_countnumber · default: 1 -
Only return values that are found in more than
min_doc_counthits. -
missingboolean | number | string -
The value to apply to documents that do not have a value. By default, documents without a value are ignored.
-
orderunion -
Specifies the sort order of the buckets. Defaults to sorting by descending document count.
-
shard_min_doc_countnumber -
Regulates the certainty a shard has if the term should actually be added to the candidate list or not with respect to the
min_doc_count. Terms will only be considered if their local shard frequency within the set is higher than theshard_min_doc_count. -
shard_sizenumber -
The number of candidate terms produced by each shard. By default,
shard_sizewill be automatically estimated based on the number of shards and thesizeparameter. -
sourceobject -
The source of the data for the transform.
-
indexstringrequired -
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-*"]. For remote indices use the syntax"remote_name:index_name". If any indices are in remote clusters then the master node and at least one transform node must have theremote_cluster_clientnode role. -
settingsobject -
Defines optional transform settings.
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align_checkpointsboolean · default: true -
Specifies whether the transform checkpoint ranges should be optimized for performance. Such optimization can align checkpoint ranges with the date histogram interval when date histogram is specified as a group source in the transform config. As a result, less document updates in the destination index will be performed thus improving overall performance.
-
dates_as_epoch_millisboolean · default: false -
Defines if dates in the ouput should be written as ISO formatted string or as millis since epoch. epoch_millis was the default for transforms created before version 7.11. For compatible output set this value to
true. -
deduce_mappingsboolean · default: true -
Specifies whether the transform should deduce the destination index mappings from the transform configuration.
-
docs_per_secondnumber -
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_sizenumber -
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
10and the maximum is65,536. The default value is500forpivottransforms and5000forlatesttransforms. -
use_point_in_timeboolean · default: true -
Specifies whether the transform checkpoint will use the Point In Time API while searching over the source index. In general, Point In Time is an optimization that will reduce pressure on the source index by reducing the amount of refreshes and merges, but it can be expensive if a large number of Point In Times are opened and closed for a given index. The benefits and impact depend on the data being searched, the ingest rate into the source index, and the amount of other consumers searching the same source index.
- Reference
-
num_failure_retriesnumber -
Defines the number of retries on a recoverable failure before the transform task is marked as
failed. The minimum value is0and the maximum is100, where-1indicates that the transform retries indefinitely. If unset, the cluster-level settingnum_transform_failure_retriesis used.This setting cannot be specified when
unattendedistrue, because unattended transforms always retry indefinitely.
Response
-
generated_dest_indexobjectrequired -
aliasesmap string to object -
<string>object -
filterQuery -
Query used to limit documents the alias can access.
-
index_routingstring -
Value used to route indexing operations to a specific shard. If specified, this overwrites the
routingvalue for indexing operations. -
If
true, the alias is hidden. All indices for the alias must have the sameis_hiddenvalue. -
lifecycleobject -
Data stream lifecycle applicable if this is a data stream.
-
data_retentionstring -
If defined, every document added to this data stream will be stored at least for this time frame. Any time after this duration the document could be deleted. When empty, every document in this data stream will be stored indefinitely.
-
retention_determined_by -
Configuration source that can influence the retention of a data stream.
-
Values:
data_stream_configurationdefault_global_retentionmax_global_retentiondefault_failures_retention -
downsamplingobject -
The list of downsampling rounds to execute as part of this downsampling configuration