Line Protocol Reference

Warning! This page documents an old version of InfluxDB, which is no longer actively developed. InfluxDB v1.3 is the most recent stable version of InfluxDB.

The Line Protocol is a text based format for writing points to InfluxDB.

Line Protocol

Syntax

<measurement>[,<tag_key>=<tag_value>[,<tag_key>=<tag_value>]] <field_key>=<field_value>[,<field_key>=<field_value>] [<timestamp>]

Each line, separated by the newline character \n, represents a single point in InfluxDB. Line Protocol is whitespace sensitive.

Description of Syntax

Line Protocol informs InfluxDB of the data’s measurement, tag set, field set, and timestamp.

Element Optional/Required Description Type
(See data types for more information.)
Measurement Required The measurement name. InfluxDB accepts one measurement per point. String
Tag set Optional All tag key-value pairs for the point. Tag keys and tag values are both strings.
Field set Required. Points must have at least one field. All field key-value pairs for the point. Field keys are strings. Field values can be floats, integers, strings, or booleans.
Timestamp Optional. InfluxDB uses the server’s local nanosecond timestamp in UTC if the timestamp is not included with the point. The timestamp for the data point. InfluxDB accepts one timestamp per point. Unix nanosecond timestamp. Specify alternative precisions with the HTTP API.

Performance and Setup Tips:

  • Sort tags by key before sending them to the database. The sort should match the results from the Go bytes.Compare function.
  • Use the coarsest precision possible for timestamps. This can result in significant improvements in compression.
  • 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

Datatype Element(s) Description
Float Field values IEEE-754 64-bit floating-point numbers. This is the default numerical type. Examples: 1, 1.0, 1.e+78, 1.E+78.
Integer Field values Signed 64-bit integers (-9223372036854775808 to 9223372036854775807). Specify an integer with a trailing i on the number. Example: 1i.
String Measurements, tag keys, tag values, field keys, field values Length limit 64KB.
Boolean Field values Stores TRUE or FALSE values.

TRUE write syntax:[t, T, true, True, TRUE].

FALSE write syntax:[f, F, false, False, FALSE]
Timestamp Timestamps Unix nanosecond timestamp. Specify alternative precisions with the HTTP API. 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.

Boolean syntax for writes vs. queries

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

Field type discrepancies

Within a measurement, a field’s type cannot differ within a shard, but it can differ across shards. See Frequently Asked Questions for how field value type discrepancies can affect SELECT * queries.

Examples

Example 1: Write the field value 1.0 as a float to InfluxDB

> INSERT mymeas value=1.0

Example 2: Write the field value 1 as a float to InfluxDB

> INSERT mymeas value=1

Example 3: Write the field value -1.234456e+78 as a float to InfluxDB

> INSERT mymeas value=-1.234456e+78

InfluxDB supports field values specified in scientific notation.

Example 4: Write the field value 1 as an integer to InfluxDB

> INSERT mymeas value=1i

Example 5: Write the field value stringing along as a string to InfluxDB

> INSERT mymeas value="stringing along"

Always double quote string field values. More on quoting below.

Example 6: Write the field value true as a boolean to InfluxDB

> INSERT mymeas value=true

Do not quote boolean field values. The following statement writes true as a string field value to InfluxDB:

> INSERT mymeas value="true"

Example 7: Attempt to write a string to a field that previously accepted floats

If the timestamps on the float and string are stored in the same shard:

> INSERT mymeas value=3 1465934559000000000
> INSERT mymeas value="stringing along" 1465934559000000001
ERR: {"error":"field type conflict: input field \"value\" on measurement \"mymeas\" is type string, already exists as type float"}

If the timestamps on the float and string are not stored in the same shard:

> INSERT mymeas value=3 1465934559000000000
> INSERT mymeas value="stringing along" 1466625759000000000
>

Quoting, Special Characters, and Additional Naming Guidelines

Quoting

Element Double quotes Single quotes
Timestamp Never Never
Measurements, tag keys, tag values, field keys Never* Never*
Field values Double quote string field values. Do not double quote floats, integers, or booleans. Never

* Line Protocol allows users to double and single quote measurement names, tag keys, tag values, and field keys. It will, however, assume that the double or single quotes are part of the name, key, or value. This can complicate query syntax (see the example below).

Examples

Example 1: Invalid Line Protocol - Double quote the timestamp


> INSERT mymeas value=9 "1466625759000000000"
ERR: {"error":"unable to parse 'mymeas value=9 \"1466625759000000000\"': bad timestamp"}

Double quoting (or single quoting) the timestamp yields a bad timestamp error.

Example 2: Semantic error - Double quote a boolean field value


> INSERT mymeas value="true"
> SHOW FIELD KEYS FROM "mymeas"
name: mymeas
------------
fieldKey	 fieldType
value		   string

InfluxDB assumes that all double quoted field values are strings.

Example 3: Semantic error - Double quote a measurement name


> INSERT "mymeas" value=200
> SHOW MEASUREMENTS
name: measurements
------------------
name
"mymeas"
> SELECT * FROM mymeas
> SELECT * FROM "mymeas"
> SELECT * FROM "\"mymeas\""
name: "mymeas"
--------------
time				                        value
2016-06-14T20:36:21.836131014Z	 200

If you double quote a measurement in Line Protocol, any queries on that measurement require both double quotes and escaped (\) double quotes in the FROM clause.

Special Characters

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

  • commas ,
  • equal signs =
  • spaces

For measurements always use a backslash character \ to escape:

  • commas ,
  • spaces

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

  • double quotes "

Line Protocol does not require users to escape the backslash character \. Users do not need to escape all other special characters.

Examples

Example 1: Write a point with special characters


> INSERT "measurement\ with\ quo⚡️es\ and\ emoji",tag\ key\ with\ sp🚀ces=tag\,value\,with"commas" field_k\ey="string field value, only \" need be esc🍭ped"

The system writes a point where the measurement is "measurement with quo⚡️es and emoji", the tag key is tag key with sp🚀ces, the tag value is tag,value,with"commas", the field key is field_k\ey and the field value is string field value, only " need be esc🍭ped.

Additional Naming Guidelines

# at the beginning of the line is a valid comment character for Line Protocol. InfluxDB will ignore all subsequent characters until the next newline \n.

Measurement names, tag keys, tag values, field keys, and field values are case sensitive.

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. In versions 1.2.0-1.2.3, InfluxDB accepts writes with time as a field or tag key but it silently drops the field key or tag key and its associated value. In version 1.2.4, InfluxDB rejects writes with time as a field key or tag key and returns an error. See Frequently Asked Questions for more information.

Line Protocol in Practice

See the Tools section for how to write Line Protocol to the database.

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.