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Find field structure APIedit

Finds the structure of a field in an Elasticsearch index.

Requestedit

GET _text_structure/find_field_structure

Prerequisitesedit

  • If the Elasticsearch security features are enabled, you must have monitor_text_structure or monitor cluster privileges to use this API. See Security privileges.

Descriptionedit

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.

Details of the output can be seen in the examples.

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.

Query parametersedit

index
(Required, string) The name of the index containing the field.
field
(Required, string) The name of the field that’s analyzed.
column_names
(Optional, string) If you have set format 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", etc.
delimiter
(Optional, 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
(Optional, unsigned integer) The number of documents to include in the structural analysis. The minimum is 2; the default is 1000.
explain
(Optional, Boolean) If true, the response includes a field named explanation, which is an array of strings that indicate how the structure finder produced its result. The default value is false.
format
(Optional, string) The high level structure of the text. Valid values are ndjson, xml, delimited, and semi_structured_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.
grok_pattern
(Optional, string) If you have set format to 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.
ecs_compatibility
(Optional, string) 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. Valid values are disabled and v1. The default value is disabled. 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 meaning then generic field names such as path, ipaddress, field1 and field2 are used in the grok_pattern output, with the intention that a user who knows the meanings rename these fields before using it.
quote
(Optional, string) If you have set format to 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
(Optional, Boolean) If you have set format to 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
(Optional, time units) Sets the maximum amount of time that the structure analysis may take. If the analysis is still running when the timeout expires then it will be stopped. The default value is 25 seconds.
timestamp_field

(Optional, string) The name of the field that contains the primary timestamp of each record in the text. In particular, if the text were 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

(Optional, 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 separated from the ss by a ., , or :. Spacing and punctuation is also permitted with the exception of ?, 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.

The following table provides the appropriate timeformat values for some example timestamps:

Timeformat Presentation

yyyy-MM-dd HH:mm:ssZ

2019-04-20 13:15:22+0000

EEE, d MMM yyyy HH:mm:ss Z

Sat, 20 Apr 2019 13:15:22 +0000

dd.MM.yy HH:mm:ss.SSS

20.04.19 13:15:22.285

Refer to the Java date/time format documentation for more information about date and time format syntax.

Examplesedit

Analyzing Elasticsearch log filesedit

Suppose you have a list of Elasticsearch log messages in an index. You can analyze them with the find_field_structure endpoint as follows:

POST _bulk?refresh=true
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:36,256][INFO ][o.a.l.u.VectorUtilPanamaProvider] [laptop] Java vector incubator API enabled; uses preferredBitSize=128"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,038][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [repository-url]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,042][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [rest-root]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,043][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-core]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,043][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-redact]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,043][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [ingest-user-agent]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-monitoring]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [repository-s3]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-analytics]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-ent-search]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-autoscaling]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [lang-painless]]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,059][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [lang-expression]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:41,059][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-eql]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:43,291][INFO ][o.e.e.NodeEnvironment    ] [laptop] heap size [16gb], compressed ordinary object pointers [true]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:46,098][INFO ][o.e.x.s.Security         ] [laptop] Security is enabled"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:47,227][INFO ][o.e.x.p.ProfilingPlugin  ] [laptop] Profiling is enabled"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:47,259][INFO ][o.e.x.p.ProfilingPlugin  ] [laptop] profiling index templates will not be installed or reinstalled"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:47,755][INFO ][o.e.i.r.RecoverySettings ] [laptop] using rate limit [40mb] with [default=40mb, read=0b, write=0b, max=0b]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:47,787][INFO ][o.e.d.DiscoveryModule    ] [laptop] using discovery type [multi-node] and seed hosts providers [settings]"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:49,188][INFO ][o.e.n.Node               ] [laptop] initialized"}
{"index":{"_index":"test-logs"}}
{"message":"[2024-03-05T10:52:49,199][INFO ][o.e.n.Node               ] [laptop] starting ..."}

GET _text_structure/find_field_structure?index=test-logs&field=message

If the request does not encounter errors, you receive the following result:

{
  "num_lines_analyzed" : 22,
  "num_messages_analyzed" : 22,
  "sample_start" : "[2024-03-05T10:52:36,256][INFO ][o.a.l.u.VectorUtilPanamaProvider] [laptop] Java vector incubator API enabled; uses preferredBitSize=128\n[2024-03-05T10:52:41,038][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [repository-url]\n", 
  "charset" : "UTF-8",
  "format" : "semi_structured_text",
  "multiline_start_pattern" : "^\\[\\b\\d{4}-\\d{2}-\\d{2}[T ]\\d{2}:\\d{2}",
  "grok_pattern" : "\\[%{TIMESTAMP_ISO8601:timestamp}\\]\\[%{LOGLEVEL:loglevel} \\]\\[.*",
  "ecs_compatibility" : "disabled",
  "timestamp_field" : "timestamp",
  "joda_timestamp_formats" : [
    "ISO8601"
  ],
  "java_timestamp_formats" : [
    "ISO8601"
  ],
  "need_client_timezone" : true,
  "mappings" : {
    "properties" : {
      "@timestamp" : {
        "type" : "date"
      },
      "loglevel" : {
        "type" : "keyword"
      },
      "message" : {
        "type" : "text"
      }
    }
  },
  "ingest_pipeline" : {
    "description" : "Ingest pipeline created by text structure finder",
    "processors" : [
      {
        "grok" : {
          "field" : "message",
          "patterns" : [
            "\\[%{TIMESTAMP_ISO8601:timestamp}\\]\\[%{LOGLEVEL:loglevel} \\]\\[.*"
          ],
          "ecs_compatibility" : "disabled"
        }
      },
      {
        "date" : {
          "field" : "timestamp",
          "timezone" : "{{ event.timezone }}",
          "formats" : [
            "ISO8601"
          ]
        }
      },
      {
        "remove" : {
          "field" : "timestamp"
        }
      }
    ]
  },
  "field_stats" : {
    "loglevel" : {
      "count" : 22,
      "cardinality" : 1,
      "top_hits" : [
        {
          "value" : "INFO",
          "count" : 22
        }
      ]
    },
    "message" : {
      "count" : 22,
      "cardinality" : 22,
      "top_hits" : [
        {
          "value" : "[2024-03-05T10:52:36,256][INFO ][o.a.l.u.VectorUtilPanamaProvider] [laptop] Java vector incubator API enabled; uses preferredBitSize=128",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,038][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [repository-url]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,042][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [rest-root]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,043][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [ingest-user-agent]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,043][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-core]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,043][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-redact]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [lang-painless]]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [repository-s3]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-analytics]",
          "count" : 1
        },
        {
          "value" : "[2024-03-05T10:52:41,044][INFO ][o.e.p.PluginsService     ] [laptop] loaded module [x-pack-autoscaling]",
          "count" : 1
        }
      ]
    },
    "timestamp" : {
      "count" : 22,
      "cardinality" : 14,
      "earliest" : "2024-03-05T10:52:36,256",
      "latest" : "2024-03-05T10:52:49,199",
      "top_hits" : [
        {
          "value" : "2024-03-05T10:52:41,044",
          "count" : 6
        },
        {
          "value" : "2024-03-05T10:52:41,043",
          "count" : 3
        },
        {
          "value" : "2024-03-05T10:52:41,059",
          "count" : 2
        },
        {
          "value" : "2024-03-05T10:52:36,256",
          "count" : 1
        },
        {
          "value" : "2024-03-05T10:52:41,038",
          "count" : 1
        },
        {
          "value" : "2024-03-05T10:52:41,042",
          "count" : 1
        },
        {
          "value" : "2024-03-05T10:52:43,291",
          "count" : 1
        },
        {
          "value" : "2024-03-05T10:52:46,098",
          "count" : 1
        },
        {
          "value" : "2024-03-05T10:52:47,227",
          "count" : 1
        },
        {
          "value" : "2024-03-05T10:52:47,259",
          "count" : 1
        }
      ]
    }
  }
}

For a detailed description of the response format, or for additional examples on ingesting delimited text (such as CSV) or newline-delimited JSON, refer to the examples of the find text structure endpoint.

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