Line Protocol Tutorial

InfluxDB’s Line Protocol is a text based format for writing points to the database. Points must be in Line Protocol format for InfluxDB to successfully parse and write points (unless you’re using a service plugin).

Using fictional temperature data, this page introduces Line Protocol. It covers:

Syntax Data Types Quoting Special Characters and Keywords

The final section, Writing data to InfluxDB, describes how to get data into InfluxDB and how InfluxDB handles Line Protocol duplicates.

Syntax

A single line of Line Protocol represents one data point in InfluxDB. It informs InfluxDB of the point’s measurement, tag set, field set, and timestamp. The following code block shows a sample of Line Protocol and breaks it into its individual components:

weather,location=us-midwest temperature=82 1465839830100400200
  |    -------------------- --------------  |
  |             |             |             |
  |             |             |             |
+-----------+--------+-+---------+-+---------+
|measurement|,tag_set| |field_set| |timestamp|
+-----------+--------+-+---------+-+---------+

Moving across each element in the diagram:

Measurement

The name of the measurement that you want to write your data to. The measurement is required in Line Protocol.

In the example, the measurement name is weather.

Tag set

The tag(s) that you want to include with your data point. Tags are optional in Line Protocol. Notice that the measurement and tag set are separated by a comma and no spaces.

Separate tag key-value pairs with an equals sign = and no spaces:

<tag_key>=<tag_value>

Separate multiple tag-value pairs with a comma and no spaces:

<tag_key>=<tag_value>,<tag_key>=<tag_value>

In the example, the tag set consists of one tag: location=us-midwest. Adding another tag (season=summer) to the example looks like this:

weather,location=us-midwest,season=summer temperature=82 1465839830100400200

For best performance you should sort tags by key before sending them to the database. The sort should match the results from the Go bytes.Compare function.

Whitespace I

Separate the measurement and the field set or, if you’re including a tag set with your data point, separate the tag set and the field set with a whitespace. The whitespace is required in Line Protocol.

Valid Line Protocol with no tag set:

weather temperature=82 1465839830100400200

Field set

The field(s) for your data point. Every data point requires at least one field in Line Protocol.

Separate field key-value pairs with an equals sign = and no spaces:

<field_key>=<field_value>

Separate multiple field-value pairs with a comma and no spaces:

<field_key>=<field_value>,<field_key>=<field_value>

In the example, the field set consists of one field: temperature=82. Adding another field (bug_concentration=98) to the example looks like this:

weather,location=us-midwest temperature=82,bug_concentration=98 1465839830100400200

Whitespace II

Separate the field set and the optional timestamp with a whitespace. The whitespace is required in Line Protocol if you’re including a timestamp.

Timestamp

The timestamp for your data point in nanosecond-precision Unix time. The timestamp is optional in Line Protocol. If you do not specify a timestamp for your data point InfluxDB uses the server’s local nanosecond timestamp in UTC.

In the example, the timestamp is 1465839830100400200 (that’s 2016-06-13T17:43:50.1004002Z in RFC3339 format). The Line Protocol below is the same data point but without the timestamp. When InfluxDB writes it to the database it uses your server’s local timestamp instead of 2016-06-13T17:43:50.1004002Z.

weather,location=us-midwest temperature=82

Use the HTTP API to specify timestamps with a precision other than nanoseconds, such as microseconds, milliseconds, or seconds. We recommend using the coarsest precision possible as this can result in significant improvements in compression. See the API Reference for more information.

Setup Tip:

Use the Network Time Protocol (NTP) to synchronize time between hosts. InfluxDB uses a host’s local time in UTC to assign timestamps to data; if hosts’ clocks aren’t synchronized with NTP, the timestamps on the data written to InfluxDB can be inaccurate.

Data types

This section covers the data types of Line Protocol’s major components: measurements, tag keys, tag values, field keys, field values, and timestamps.

Measurements, tag keys, tag values, and field keys are always strings.

Note: Because InfluxDB stores tag values as strings, InfluxDB cannot perform math on tag values. In addition, InfluxQL functions do not accept a tag value as a primary argument. It’s a good idea to take into account that information when designing your schema.

Timestamps are UNIX timestamps. The minimum valid timestamp is -9223372036854775806 or 1677-09-21T00:12:43.145224194Z. The maximum valid timestamp is 9223372036854775806 or 2262-04-11T23:47:16.854775806Z. As mentioned above, by default, InfluxDB assumes that timestamps have nanosecond precision. See the API Reference for how to specify alternative precisions.

Field values can be floats, integers, strings, or booleans:

  • Floats - by default, InfluxDB assumes all numerical field values are floats.

    Store the field value 82 as a float:

    weather,location=us-midwest temperature=82 1465839830100400200

  • Integers - append an i to the field value to tell InfluxDB to store the number as an integer.

    Store the field value 82 as an integer:

    weather,location=us-midwest temperature=82i 1465839830100400200

  • Strings - double quote string field values (more on quoting in Line Protocol below).

    Store the field value too warm as a string:

    weather,location=us-midwest temperature="too warm" 1465839830100400200

  • Booleans - specify TRUE with t, T, true, True, or TRUE. Specify FALSE with f, F, false, False, or FALSE.

    Store the field value true as a boolean:

    weather,location=us-midwest too_hot=true 1465839830100400200

    Note: Acceptable boolean syntax differs for data writes and data queries. See Frequently Asked Questions for more information.

Within a measurement, a field’s type cannot differ within a shard, but it can differ across shards. For example, writing an integer to a field that previously accepted floats fails if InfluxDB attempts to store the integer in the same shard as the floats:

> INSERT weather,location=us-midwest temperature=82 1465839830100400200
> INSERT weather,location=us-midwest temperature=81i 1465839830100400300
ERR: {"error":"field type conflict: input field \"temperature\" on measurement \"weather\" is type int64, already exists as type float"}

But, writing an integer to a field that previously accepted floats succeeds if InfluxDB stores the integer in a new shard:

> INSERT weather,location=us-midwest temperature=82 1465839830100400200
> INSERT weather,location=us-midwest temperature=81i 1467154750000000000
>

See Frequently Asked Questions for how field value type discrepancies can affect SELECT * queries.

Quoting

This section covers when not to and when to double (") or single (') quote in Line Protocol. Moving from never quote to please do quote:

  • Never double or single quote the timestamp. It’s not valid Line Protocol.

    Example:

    > INSERT weather,location=us-midwest temperature=82 "1465839830100400200"
ERR: {"error":"unable to parse 'weather,location=us-midwest temperature=82 \"1465839830100400200\"': bad timestamp"}

  • Never single quote field values (even if they’re strings!). It’s also not valid Line Protocol.

    Example:

    > INSERT weather,location=us-midwest temperature='too warm'
ERR: {"error":"unable to parse 'weather,location=us-midwest temperature='too warm'': invalid boolean"}

  • Do not double or single quote measurement names, tag keys, tag values, and field keys. It is valid Line Protocol but InfluxDB assumes that the quotes are part of the name.

    Example:

    > INSERT weather,location=us-midwest temperature=82 1465839830100400200
> INSERT "weather",location=us-midwest temperature=87 1465839830100400200
> SHOW MEASUREMENTS
name: measurements
------------------
name
"weather"
weather

    To query data in "weather" you need to double quote the measurement name and escape the measurement’s double quotes:

    > SELECT * FROM "\"weather\""
name: "weather"
---------------
time                            location     temperature
2016-06-13T17:43:50.1004002Z    us-midwest   87

  • Do not double quote field values that are floats, integers, or booleans. InfluxDB will assume that those values are strings.

    Example:

    > INSERT weather,location=us-midwest temperature="82"
> SELECT * FROM weather WHERE temperature >= 70
>

  • Do double quote field values that are strings.

    Example:

    > INSERT weather,location=us-midwest temperature="too warm"
> SELECT * FROM weather
name: weather
-------------
time                            location     temperature
2016-06-13T19:10:09.995766248Z  us-midwest   too warm

Special characters and keywords

Special characters

For tag keys, tag values, and field keys always use a backslash character \ to escape:

  • commas ,

    weather,location=us\,midwest temperature=82 1465839830100400200

  • equal signs =

    weather,location=us-midwest temp\=rature=82 1465839830100400200

  • spaces

    weather,location\ place=us-midwest temperature=82 1465839830100400200

For measurements always use a backslash character \ to escape:

  • commas ,

    wea\,ther,location=us-midwest temperature=82 1465839830100400200

  • spaces

    wea\ ther,location=us-midwest temperature=82 1465839830100400200

For string field values use a backslash character \ to escape:

  • double quotes "

    weather,location=us-midwest temperature="too\"hot\"" 1465839830100400200

Line Protocol does not require users to escape the backslash character \. All other special characters also do not require escaping. For example, Line Protocol handles emojis with no problem:

> INSERT we⛅️ther,location=us-midwest temper????ture=82 1465839830100400200
> SELECT * FROM "we⛅️ther"
name: we⛅️ther
------------------
time			              location	   temper????ture
1465839830100400200	 us-midwest	 82

Keywords

Line Protocol accepts InfluxQL keywords as identifier names. In general, we recommend avoiding using InfluxQL keywords in your schema as it can cause confusion when querying the data.

The keyword time is a special case. time can be a continuous query name, database name, measurement name, retention policy name, subscription name, and user name. In those cases, time does not require double quotes in queries. time cannot be a field key or tag key; InfluxDB rejects writes with time as a field key or tag key and returns an error. See Frequently Asked Questions for more information.

Writing data to InfluxDB

Getting data in the database

Now that you know all about Line Protocol, how do you actually get the Line Protocol to InfluxDB? Here, we’ll give two quick examples and then point you to the Tools sections for further information.

HTTP API

Write data to InfluxDB using the HTTP API. Send a POST request to the /write endpoint and provide your Line Protocol in the request body:

curl -i -XPOST "http://localhost:8086/write?db=science_is_cool" --data-binary 'weather,location=us-midwest temperature=82 1465839830100400200'

For in-depth descriptions of query string parameters, status codes, responses, and more examples, see the API Reference.

CLI

Write data to InfluxDB using InfluxDB’s Command Line Interface (CLI). Launch the CLI, use the relevant database, and put INSERT in front of your Line Protocol:

INSERT weather,location=us-midwest temperature=82 1465839830100400200

You can also use the CLI to import Line Protocol from a file.

There are several ways to write data to InfluxDB. See the Tools section for more on the HTTP API, the CLI, and the available Service Plugins ( UDP, Graphite, CollectD, and OpenTSDB).

Duplicate points

A point is uniquely identified by the measurement name, tag set, and timestamp. If you submit Line Protocol with the same measurement, tag set, and timestamp, but with a different field set, the field set becomes the union of the old field set and the new field set, where any conflicts favor the new field set.

See Frequently Asked Questions for a complete example of this behavior and how to avoid it.

© 2015 InfluxData, Inc.
Licensed under the MIT license.
https://docs.influxdata.com/influxdb/v1.3/write_protocols/line_protocol_tutorial/