Find the structure of a text field

GET /_text_structure/find_field_structure

Auth

Find the structure of a text field in an Elasticsearch index.

This API provides a starting point for extracting further information from log messages already ingested into Elasticsearch. For example, if you have ingested data into a very simple index that has just @timestamp and message fields, you can use this API to see what common structure exists in the message field.

The response from the API contains:

Sample messages.
Statistics that reveal the most common values for all fields detected within the text and basic numeric statistics for numeric fields.
Information about the structure of the text, which is useful when you write ingest configurations to index it or similarly formatted text.
Appropriate mappings for an Elasticsearch index, which you could use to ingest the text.

All this information can be calculated by the structure finder with no guidance. However, you can optionally override some of the decisions about the text structure by specifying one or more query parameters.

If the structure finder produces unexpected results, specify the explain query parameter and an explanation will appear in the response. It helps determine why the returned structure was chosen.

Required privileges

Cluster privileges monitor_text_structure

Query parameters

column_names string

If format is set to delimited, you can specify the column names in a comma-separated list. If this parameter is not specified, the structure finder uses the column names from the header row of the text. If the text does not have a header row, columns are named "column1", "column2", "column3", for example.

delimiter string

If you have set format to delimited, you can specify the character used to delimit the values in each row. Only a single character is supported; the delimiter cannot have multiple characters. By default, the API considers the following possibilities: comma, tab, semi-colon, and pipe (|). In this default scenario, all rows must have the same number of fields for the delimited format to be detected. If you specify a delimiter, up to 10% of the rows can have a different number of columns than the first row.

documents_to_sample number · default: 1000

The number of documents to include in the structural analysis. The minimum value is 2.

ecs_compatibility enum · default: disabled

The mode of compatibility with ECS compliant Grok patterns. Use this parameter to specify whether to use ECS Grok patterns instead of legacy ones when the structure finder creates a Grok pattern. This setting primarily has an impact when a whole message Grok pattern such as %{CATALINALOG} matches the input. If the structure finder identifies a common structure but has no idea of the meaning then generic field names such as path, ipaddress, field1, and field2 are used in the grok_pattern output. The intention in that situation is that a user who knows the meanings will rename the fields before using them.

Values: disabled v1

explain boolean · default: false

If true, the response includes a field named explanation, which is an array of strings that indicate how the structure finder produced its result.

field string required

The field that should be analyzed.

format enum

The high level structure of the text. By default, the API chooses the format. In this default scenario, all rows must have the same number of fields for a delimited format to be detected. If the format is set to delimited and the delimiter is not set, however, the API tolerates up to 5% of rows that have a different number of columns than the first row.

Values: delimited ndjson semi_structured_text xml

grok_pattern string

If the format is semi_structured_text, you can specify a Grok pattern that is used to extract fields from every message in the text. The name of the timestamp field in the Grok pattern must match what is specified in the timestamp_field parameter. If that parameter is not specified, the name of the timestamp field in the Grok pattern must match "timestamp". If grok_pattern is not specified, the structure finder creates a Grok pattern.

index string required

The name of the index that contains the analyzed field.

quote string

If the format is delimited, you can specify the character used to quote the values in each row if they contain newlines or the delimiter character. Only a single character is supported. If this parameter is not specified, the default value is a double quote ("). If your delimited text format does not use quoting, a workaround is to set this argument to a character that does not appear anywhere in the sample.

should_trim_fields boolean

If the format is delimited, you can specify whether values between delimiters should have whitespace trimmed from them. If this parameter is not specified and the delimiter is pipe (|), the default value is true. Otherwise, the default value is false.

timeout union oneOf · default: 25s

The maximum amount of time that the structure analysis can take. If the analysis is still running when the timeout expires, it will be stopped.

Values: -1 0

timestamp_field string

The name of the field that contains the primary timestamp of each record in the text. In particular, if the text was ingested into an index, this is the field that would be used to populate the @timestamp field.

If the format is semi_structured_text, this field must match the name of the appropriate extraction in the grok_pattern. Therefore, for semi-structured text, it is best not to specify this parameter unless grok_pattern is also specified.

For structured text, if you specify this parameter, the field must exist within the text.

If this parameter is not specified, the structure finder makes a decision about which field (if any) is the primary timestamp field. For structured text, it is not compulsory to have a timestamp in the text.

timestamp_format string

The Java time format of the timestamp field in the text. Only a subset of Java time format letter groups are supported:

a
d
dd
EEE
EEEE
H
HH
h
M
MM
MMM
MMMM
mm
ss
XX
XXX
yy
yyyy
zzz

Additionally S letter groups (fractional seconds) of length one to nine are supported providing they occur after ss and are separated from the ss by a period (.), comma (,), or colon (:). Spacing and punctuation is also permitted with the exception a question mark (?), newline, and carriage return, together with literal text enclosed in single quotes. For example, MM/dd HH.mm.ss,SSSSSS 'in' yyyy is a valid override format.

One valuable use case for this parameter is when the format is semi-structured text, there are multiple timestamp formats in the text, and you know which format corresponds to the primary timestamp, but you do not want to specify the full grok_pattern. Another is when the timestamp format is one that the structure finder does not consider by default.

If this parameter is not specified, the structure finder chooses the best format from a built-in set.

If the special value null is specified, the structure finder will not look for a primary timestamp in the text. When the format is semi-structured text, this will result in the structure finder treating the text as single-line messages.

Response

application/json

charset string required
ecs_compatibility enum: Values: disabled v1
field_stats map string to object required
format enum required: Values: delimited ndjson semi_structured_text xml
grok_pattern string
java_timestamp_formats string[]
joda_timestamp_formats string[]
ingest_pipeline object required
mappings object required
multiline_start_pattern string
need_client_timezone boolean required
num_lines_analyzed number required
num_messages_analyzed number required
sample_start string required
timestamp_field string